Anti-Lock Braking System Training Program

COVERST.EPS ac T to $2.50 BS A Anti-Lock Baking System Taining Pogam Student Manual TP-9738 Revised 3-99 Module 1 ABS Components and System Opeation Module 2 ABS Diagnosis and Repai Module 3 ATC Opeation, Diagnosis and Repai

Module 1 ABS Components and System Opeation Table of Contents Definition of Tems...................................... 2 ABS System Oveview and Components.................... 3 System Opeation....................................... 17 1-1

Module 1 ABS Components and System Opeation Definition of Tems ABS Configuation Thei ae thee available ABS configuations. The configuation name is based on the numbe of modulato valves and sensos on the vehicle. The thee configuations ae 4S/4M, 6S/4M and 6S/6M (S = Sensos and M = ABS Modulato valves). ABS Modulato Valve Electopneumatic contol valve that contains the solenoids used fo contolling ai pessue. They can pecisely modulate ai pessue duing an ABS-contolled bake application. Electonic Contol Unit (ECU) The ECU contains the computes that take the input signals, pocesses the infomation and then sends output signals to the necessay components. The ECU contols the anti-lock bake and automatic taction contol systems, as well as the diagnostic functions. Solenoid A device that convets an electical signal into mechanical movement. It consists of a coil with a moveable coe that changes positions by means of electomagnetism when cuent flows though the coil. Tooth Wheel A metal ing, nomally with 100 evenly spaced teeth. The tooth wheel could have 80 o 120 teeth, based on extemely small o extemely lage ties. It is usually attached to the bael of the hub on each ABS-monitoed wheel. When the wheel otates, the teeth move past the wheel speed senso to ceate an electical signal that the ECU uses to detemine wheel speed. Wheel Speed Senso A magnetic pickup-type senso positioned nea a wheel that poduces a signal to indicate wheel speed to the ECU. In geneal, a senso geneates an electical signal with a fequency popotional to the wheel speed. A pemanent magnet and passing metal teeth combine to poduce a signal. The teeth alte the magnetic field poduced by the senso. The changing magnetic field poduces AC voltages in pickup coils within the senso. In ABS applications, these signals ae elayed to the ECU, which pocesses them to detemine wheel speed. Fou-Channel ABS A system that has fou sensos and fou ABS modulato valves (4S/4M). The system may also have six sensos and fou ABS modulato valves (6S/4M). Six-Channel ABS A system that has six sensos and six ABS modulato valves (6S/6M). 1-2

ABS System Oveview and Components Table of Contents Section Oveview........................................ 4 Anti-Lock Baking System (ABS) Oveview................. 5 ABS Oveview....................................... 5 ABS Opeation Summay.............................. 5 ABS Featues and Benefits.............................. 6 ABS Components....................................... 7 Wheel-Speed Sensing System Components............... 7 Tooth Wheel.......................................... 7 Wheel Speed Senso................................... 8 Senso Holde and Sping Clip.......................... 8 Senso Extension Cable................................ 8 Electonic Contol Unit (ECU).......................... 9 ECU Types........................................... 9 ABS Modulato Valve................................. 11 Vehicle Wheel/ABS Configuations.................... 13 ABS Indicato Lamp................................. 13 Blink Code Switch................................... 13 J-1587 Diagnostic Connecto........................... 13 Section Summay...................................... 15 Pogess Check 1-1..................................... 16 1-3

ABS System Oveview and Components Section Oveview This section intoduces the basics of the Meito WABCO anti-lock baking system with D-vesion electonic contol unit. It also discusses specific featues and benefits of the Meito WABCO system. Afte completing this section, the technician will be able to: Descibe the basic functions of the Meito WABCO ABS. Intepet ABS indicato lamps. Explain the ABS featues that can aid in diagnostics and toubleshooting. Locate wheel speed sensos, ABS valves and ABS lamps. Identify the ECU and descibe how it communicates with othe components. Identify the diffeent ABS configuations. NOTE: View video tape segment numbe one. Retun to this wokbook when instucted to by the video tape and ead the est of Module One. 1-4

ABS System Oveview and Components ANTI-LOCK BRAKING SYSTEM (ABS) OVERVIEW ABS Oveview The anti-lock baking system modulates the ai pessue in the bake chambes to pevent wheel lockup and povide pecise baking contol duing ove-baking. This enhances: Vehicle stability Steeability unde emegency baking Stable stopping on icy o ain-slicked oad sufaces and in cuves Stopping distance ABS also educes the possibility of: Jackknifing o plowout (loss of steeing contol) Tie flatspotting ABS Opeation Summay ABS takes ove contol of the ai pessue wheneve a wheel stats to lock up. Sensos continuously monito wheel speed and send this infomation to an Electonic Contol Unit (ECU). When a wheel stats to lock, the ECU, using the wheel-speed infomation and pogammed data, sends output signals to contol the opeation of the ABS valves. The ECU causes the ABS valves to adjust ai pessue supplied to the bake chambes to contol baking and pevent wheel lockup. 1-5

ABS System Oveview and Components ABS Featues and Benefits Featues Benefits Individual contol of steeing and dive wheels Fail-safe system Automatic taction contol (optional) Inceased stability and dive contol educes possibility of jackknifing and keeps steeing contol. If system malfunctions, ABS is shut off at the affected wheel end(s), etuning affected wheel(s) to nomal baking. Contols excessive wheel spin duing acceleation. Self diagnostic system Built-in system makes maintenance checks quick and easy. Diagnostic tool compatibility Blink code switch ABS indicato lamp Can use industy-standad electonic diagnostic tools. Po-Link 9000 diagnostic tool has a catidge designed specifically fo Meito WABCO ABS/ATC systems. Standad switch allows access to fault codes without the use of a diagnostic tool. Infoms vehicle opeato that an ABS fault has been detected. The lamp is also used fo displaying diagnostic blink codes on D vesion ABS. 1-6

ABS System Oveview and Components ABS COMPONENTS Wheel-Speed Sensing System Components Tooth Wheel The ECU uses input fom the wheel-speed sensing system to detemine when to activate ABS and ATC opeation. The following components compise the system: Tooth wheel Wheel speed senso Senso holde and sping clip Senso extension cable The tooth wheel nomally has 100 evenly spaced teeth and is usually mounted to the bael of the hub on each sensed wheel. Tooth Wheel 1-7

ABS System Oveview and Components Wheel Speed Senso Fo optimum pefomance, the pencil-type wheel speed senso is a completely sealed unit and is located in the wheel end. A vehicle will nomally have fou sensos. The sensos ae usually mounted in the flange of the steeing knuckles at each side of the steeing axle. Additional sensos ae located in senso holdes attached to the dive axle housing on one of the two tandem axles. Senso mounting location depends on the type of suspension. Typically, on a vehicle with a sping suspension, the sensos ae mounted on the fowad tandem axle. On a vehicle with an ai suspension, the sensos ae mounted on the ea tandem axle. A 6S/6M and a 6S/4M system will have two additional sensos at the second ea axle. Two senso types ae available: a ight-angle senso and a staight senso. The type used depends on the vehicle make and model. Wheel Speed Sensos Senso Holde and Sping Clip On ea wheels, the senso is mounted in senso holdes that ae welded to the axle housing. A sping clip gips the senso into the holde. Rea-Wheel Senso Holde and Sping Clip On font wheels, the senso is mounted in a bushing located in the steeing knuckle. A sping clip is used to hold the senso in the bushing. Senso Extension Cable The senso extension cable, which is pat of the ABS chassis haness, connects the senso to the ECU. 1-8

ABS System Oveview and Components Electonic Contol Unit (ECU) ECU Types The Electonic Contol Unit (ECU) handles the pocessing function of the ABS. It eceives and intepets the wheel speed signals fom the sensos and uses this infomation to detemine if a wheel is going to lock and when and how to activate the ABS valves. Though this valve actuation, the ECU can egulate ai pessue to the bake chambes. Cab and chassis hanesses connect the ECU to the following ABS components: Wheel speed sensos ABS modulato valves Powe souce Gound ABS indicato lamp Blink code switch J-1587 Diagnostic Connecto Retade contol (via elay o J1922/J1939 datalink) Thee types of electonic contol units ae available with WABCO ABS. D-Basic vesion cab-mounted ECU D vesion cab-mounted ECU D vesion fame-mounted ECU The type of ECU used and its mounting location vaies by manufactue and application. Fo moe detailed infomation, consult the vehicle manufactue s sevice liteatue. The D-Basic vesion ECU is smalle than the othe two vesions, and has only two connecto pots. The D-Basic ECU is used exclusively with vehicles that only have ABS and do not have optional ATC. The D-Basic ECU is mounted within the vehicle cab. D-Basic Vesion Electonic Contol Unit 1-9

ABS System Oveview and Components ECU Types (Cont.) The fou-channel (4S/4M) D vesion cab-mounted ECU has fou connecto pots. The 6S/4M and 6S/6M ECUs have a fifth connecto pot. The ECU is capable of contolling both the ABS and ATC systems. The mounting location of the ECU within the cab will vay depending on vehicle make and model. Consult you vehicle manufactue s sevice publications fo the exact mounting location. CAB-MOUNTED ECU FRAME-MOUNTED ECU D Vesion Electonic Contol Units The D vesion fame-mounted ECU has thee connecto pots on vehicles equipped with fou-channel ABS. The fouth connecto pot is used on 6S/4M and 6S/6M systems. Bolted-down coves secue the convoluted tubing potecting the chassis haness. This ECU can be mounted on a vehicle fame ail o cossmembe and is capable of contolling both the ABS and ATC systems. ECU ECU D Vesion Fame-Mounted ECU Connecto Pots 1-10

ABS System Oveview and Components ABS Modulato Valve The ABS modulato valve egulates ai pessue to each ABScontolled bake. Duing nomal baking, the ABS modulato valves ae not activated and ai flows though the ABS valve into the bake chambes. Duing ABS opeation, the ABS valves modulate ai pessue in the bake chambes to contol baking and pevent wheel lockup. The ABS valve is a solenoid-contolled ai valve, consisting of two electically opeated solenoids and two diaphagm valves. The ECU contols the solenoids, which ae extemely fast acting. They contol pessue on the diaphagms, which then open o close passages to supply pessue to, o exhaust pessue fom, the bake chambe. The ABS valve has thee ai pots: The supply pot eceives ai pessue fom the elay valve. The delivey pot delives ai pessue to the bake chambes. The exhaust pot exhausts ai pessue only fom the delivey-pot side duing ABS contol. 2 1 ABS Valve 1-11

ABS System Oveview and Components ABS Modulato Valve (Cont.) A typical 4S/4M ABS will have fou ABS valves, one fo each side of the steeing axle and one fo each side of the dive axle(s). The valves ae usually attached to a fame ail o cossmembe, between the elay valve o quick-elease valve and the bake chambe. Fo a tandem dive axle, both wheels on the same side ae contolled by a single valve. An ABS Valve Package is an altenative to individual valves on the ea axle. The ea axle package combines two ABS valves and one sevice elay valve. The font axle valve package combines two ABS valves and one quick elease valve. The valve package is usually attached to a fame cossmembe. ABS hanesses connect the valve solenoids to the ECU. xxxxx xxxxx xxxxx xxxxx ABS Rea Axle Valve Package 001 20/98 472 500 30. 0 MADE IN GERMANY ABS Font Axle Valve Package 1-12

ABS System Oveview and Components Vehicle Wheel/ABS Configuations ABS Indicato Lamp Blink Code Switch J-1587 Diagnostic Connecto Illustated on the next page ae examples of thee available Meito WABCO ABS configuations. They ae: 4S/4M Fou sensos and fou ABS modulatos valves 6S/4M Six sensos and fou ABS modulatos valves 6S/6M Six sensos and six ABS modulatos valves The ABS indicato lamp is located on the dash panel. The lamp is lit when the ABS system is pefoming a self-test o when a fault has been detected in system. The lamp is also used to display fault codes. This switch signals the ECU to activate the ABS indicato lamp so that it can blink out the fault codes. Switch types and locations vay depending on the make and model of the vehicle. The J-1587 diagnostic connecto is used to toubleshoot the ABS ECU with an electonic diagnostic tool, such as the Po Link 9000. The diagnostic connecto is usually located inside the cab and is the same connecto that is used to toubleshoot electonic engines. 1-13

ABS System Oveview and Components 4S/4M System PNEUMATIC ELECTRIC TOOTH WHEEL TOOTH WHEEL SENSOR ECU SENSOR ABS MODULATOR VALVES ABS VALVE PACKAGE SENSOR SENSOR TOOTH WHEEL TOOTH WHEEL 6S/4M System PNEUMATIC ELECTRIC TOOTH WHEEL SENSOR ECU TOOTH WHEEL SENSOR TOOTH WHEEL SENSOR ABS MODULATOR VALVES ABS VALVE PACKAGE SENSOR SENSOR SENSOR TOOTH WHEEL TOOTH WHEEL TOOTH WHEEL 6S/6M System PNEUMATIC ELECTRIC TOOTH WHEEL SENSOR ECU TOOTH WHEEL SENSOR TOOTH WHEEL SENSOR ABS MODULATOR VALVES ABS VALVE PACKAGE ABS VALVE PACKAGE SENSOR SENSOR TOOTH WHEEL SENSOR TOOTH WHEEL TOOTH WHEEL ABS Configuations 1-14

ABS System Oveview and Components Section Summay This section povided the following infomation: The basic functions of the Meito WABCO ABS. The featues and benefits of the ABS. The appeaance and locations of ABS components. The thee available ABS configuations ae 4S/4M, 6S/4M and 6S/6M (S = Sensos and M = ABS Modulato valves). The wheel-speed sensing system is compised of a tooth wheel (attached to the hub of an ABS-contolled wheel), a magnetic pickup-type senso (positioned nea the tooth wheel), a senso holde and sping clip, and a cable attaching the senso to the ECU. With a fou-channel ABS, the wheel speed sensos ae mounted to eithe the fowad-ea o the ea-ea dive axle depending type of suspension. The ABS modulato valve is a solenoid-contolled ai valve that modulates ai pessue flowing to the bake chambes. When a sensed wheel is going to lock, the valve eceives signals fom the ECU to contol ai pessue in the bake chambe and pevent the wheel fom locking. 1-15

ABS System Oveview and Components Pogess Check 1-1 Answe the questions below befoe continuing to the next section. 1. The electonic contol unit can cause the ABS to adjust ai pessue supplied to the bake chambes and contol baking and wheel lockup. 2. The blink code switch and lamp allow access to stoed fault without using a diagnostic tool. 3. The configuation designation 6S/4M indicates that the vehicle's anti-lock baking system has six and fou ABS. 4. The wheel speed senso is positioned nea the wheel attached to the wheel hub. 5. The ECU eceives and intepets all signals at the same time. 6. The ABS valve includes two electical and two diaphagm valves. 1-16

System Opeation Table of Contents Oveview................................................ 18 Inputs................................................... 19 Oveview.............................................. 19 Wheel Speed Senso Opeation........................... 20 Pocessing............................................... 22 Oveview.............................................. 22 ECU Opeation (ABS)................................... 22 Outputs................................................. 23 Output Signals......................................... 23 ABS Modulato Valve Opeation......................... 24 Nomal (Without Anti-Lock) Bake Application Supply... 24 Nomal (Without Anti-Lock) Bake Application Exhaust.. 24 Anti-Lock Bake Contol Exhaust...................... 25 Anti-Lock Bake Contol Hold......................... 26 Anti-Lock Bake Contol Reapply...................... 27 ABS Indicato Lamp.................................... 28 Retade Contol....................................... 28 Section Summay......................................... 30 Pogess Check 1-2........................................ 31 1-17

System Opeation Oveview ABS opeation can be boken down into thee basic stages o functions: Inputs Pocessing Outputs Inputs Pocessing Outputs Inputs ae compised of signals fom sensos, switches and diagnostic equipment. The ABS ECU intepets these signals and detemines an opeating stategy as pat of the pocessing function. The ECU then sends output signals to system components. These signals cause the components to function in accodance with the ECU s opeating stategy. The specifics of inputs, pocessing and outputs ae discussed in geate detail on the following pages. 1-18

System Opeation INPUTS Oveview Inputs ae electical signals sent to the ABS Electonic Contol Unit (ECU). Wheel speed sensos ae the main input fo ABS and ATC contol. This section discusses: Whee wheel speed senso components ae located How wheel speed sensos opeate Relationship between wheel speed senso components and the ECU The ECU eceives two othe inputs that ae used fo diagnostic puposes: The check switch (blink code activation) Commands fom a diagnostic tool These inputs will be coveed late in the Diagnostics and Repai module of this wokbook. 1-19

System Opeation Wheel Speed Senso Opeation The wheel speed senso is a magnetic pickup-type senso. It consists of a coil wapped aound a magnet. It is positioned nea the tooth wheel which is attached to the wheel hub. As the wheel spins, the teeth (and the spaces between them) pass by the senso. This influences the magnetic flow though the field poduced by the magnet. As the magnetic flow builds and collapses with the passing of each tooth and gap, voltage pulses ae ceated in the coil wapped aound the magnet. These pulses ae elayed to the electonic contol unit and is used to detemine the elative speed of the wheel. TIME SENSOR VOLTAGE Magnetic Pickup-Type Senso Opeation 1-20

System Opeation TOOTH WHEEL TOOTH WHEEL SENSOR BLINK CODE SWITCH SENSOR J1587 DIAGNOSTIC CONNECTOR ECU TOOTH WHEEL TOOTH WHEEL SENSOR SENSOR ABS Input Components 1-21

System Opeation PROCESSING Oveview ECU Opeation (ABS) The ECU monitos and contols ABS opeation to impove baking pefomance. The ECU also pefoms self-diagnostic outines and on-demand component tests as pat of its pocessing function. Each wheel speed senso sends an AC voltage signal to the ECU. Based on the fequency of the AC signal, the ECU constantly monitos the speed of each of the sensed wheels. When the bakes ae applied, all the wheels begin to slow down. The deceleation ate of the wheels is geate duing an aggessive o had bake application o if the vehicle is on a slippey suface. The ECU is pogammed to identify if the deceleating wheels ae going to lock. If the ECU detemines that any of the wheels ae appoaching lockup, it contols ABS valve opeation to modulate bake pessue and pevent the wheel(s) fom locking. 1-22

System Opeation OUTPUTS Output Signals The ECU sends signals o outputs to the following ABS components to contol thei opeation. ABS modulato valves ABS indicato lamp/blink code lamp Retade Contol (via elay o J1922/J1939 Data Link) J1587 Diagnostic Data Link The ECU is capable of communicating with a hand-held electonic diagnostic tool though the SAE J1587 diagnostic data link. With this tool, technicians can access and clea fault codes as well as command component tests. Diagnostic tool pocedues ae explained in the Diagnostics and Repai section of this wokbook. 1-23

System Opeation ABS Modulato Valve Opeation Nomal (Without Anti-Lock) Bake Application Supply Duing nomal baking, both solenoids in the ABS modulato valve ae de-enegized o inactive. The supply diaphagm contol chambe of the inlet valve is open to the atmosphee. Ai pessue enteing the supply pot unseats the supply diaphagm. This opens the passage to the delivey pot and allows ai pessue to flow diectly though the valve and into the bake chambe. Simultaneously, ai pessue flows past the de-enegized exhaust solenoid and puts pessue on the exhaust diaphagm. This pessue combines with sping foce to keep the exhaust diaphagm seated and close the path fom the delivey pot to the exhaust pot. The ABS valve maintains this balanced (o pessue incease) position until a wheel stats to lock. Then one o both of the solenoids ae activated by the ECU. Pessue Incease (Without Anti-Lock) Nomal (Without Anti-Lock) Bake Application Exhaust Ai pessue at the supply pot deceases when the bake pedal valve is eleased. This eveses the diection of aiflow though the valve and exhausts ai pessue fom the bake chambe. Ai can also be eleased fom the ABS valve exhaust pot duing bake elease. 1-24

System Opeation ABS Modulato Valve Opeation (Cont.) Anti-Lock Bake Contol Exhaust When the ECU detemines that a wheel is going to lock, it fist enegizes (activates) both ABS valve solenoids. The enegized supply solenoid allows ai pessue to ente the supply diaphagm contol chambe, whee it holds the supply diaphagm in the seated position. This stops any moe ai fom enteing the bake chambe. When enegized, the exhaust solenoid cuts off the supply of ai pessue enteing the exhaust diaphagm and exhausts that ai to the atmosphee. Thus, pessue fom the bake chambe entes though the delivey pot and unseats the exhaust diaphagm. This opens the passage between the delivey pot and the exhaust pot, which eleases ai pessue fom the bake chambe. Pessue Decease (Anti-Lock) 1-25

System Opeation ABS Modulato Valve Opeation (Cont.) Anti-Lock Bake Contol Hold When enough ai is eleased though the exhaust pot to stop the wheel fom locking, the exhaust solenoid is de-enegized. This seats the exhaust diaphagm and stops any moe ai fom leaving the bake chambe. The supply solenoid emains enegized to pevent ai pessue fom passing though the ABS valve. The emaining ai pessue in the bake chambe is held and emains constant. Pessue Constant 1-26

System Opeation ABS Modulato Valve Opeation (Cont.) Anti-Lock Bake Contol Reapply To achieve pope baking, the ECU monitos wheel speed and detemines when to eapply bake pessue. When necessay, both ABS valve solenoids ae de-enegized, etuning the system to the nomal bake-application supply state. The ECU cycles though the diffeent valve states (pessue incease, pessue decease and pessue hold) vey apidly in ode to contol wheel speed. The Meito WABCO ABS system achieves efficient baking by independently contolling individual wheels. Pessue Incease (Anti-Lock) Note: The vehicle opeato contols the maximum amount of pessue applied to the bakes. Pessue to the bake chambe can neve be moe than what the opeato is asking fo with his foot pedal. 1-27

System Opeation ABS Indicato Lamp The ABS indicato lamp is located on the dash panel. When the ignition switch is tuned to the ON position, it lights, indicating that the ABS is pefoming a self-test. When the self-test is complete, the lamp goes out. If the indicato lamp emains lit o comes on at any othe time duing vehicle opeation, a potential fault exists in the ABS system. Additionally, if a senso adjustment fault existed the last time the ignition was shut off, but has been epaied, the indicato lamp will not go off until the vehicle has been diven ove fou mph. This allows the ECU to veify that the fault has been coected. The ABS indicato lamp opeation is contolled eithe by the ECU o by the main connecto to the ECU. The ABS indicato lamp eceives powe fom the ignition switch wheneve it is tuned on. The othe side of the lamp is gounded both though the ECU and eithe the specially designed main connecto o an electical elay. Eithe device can complete the gound cicuit, theeby tuning on the lamp. The Meito WABCO electonic contol unit uses the ABS indicato lamp to flash blink codes, identifying specific faults in the ABS. The pocedues fo displaying, intepeting and easing blink code faults ae pesented in the Blink Code Diagnostics and Fault Analysis section of Module Two. Retade Contol Duing an ABS event, the ECU sends a signal to shut off the etade. It can do this in one of two ways: 1. Sends a 12-volt signal to enegize the coil of the etade elay. This opens the contacts and inteupts the etade switch cicuit, theeby shutting off the etade. 2. The ECU boadcasts ove the J1922/J1939 data link to the engine ECM, which in tun shuts off the etade. When the wheels ae no longe locking, the etade is automatically tuned back on. 1-28

System Opeation ABS MODULATOR VALVES ABS INDICATOR AND BLINK CODE LAMP RETARDER RELAY J1922/J1939 DATA LINK J1587 DIAGNOSTIC CONNECTOR ECU ABS VALVE PACKAGE ABS/ATC Pocessing and Output Components 1-29

System Opeation Section Summay This section povided the following infomation: Inputs ae electical signals sent to the ABS electonic contol unit. The wheel speed sensos ae input souces. The motion of the tooth wheel though a magnetic field ceated by the senso poduces an electonic signal that is sent to the ECU. The ECU pocesses the wheel-speed senso signals to detemine if a wheel is about to lock. In this case, the ECU will contol ABS valve opeation to modulate bake pessue and pevent the wheel fom locking up. The ABS modulato valve is a solenoid-contolled ai valve that can contol ai pessue flowing to, o exhausting fom, the bake chambes. Aiflow though the valve is contolled by solenoids which ae contolled by the ECU. The ABS indicato lamp indicates a self-test wheneve the ignition switch is tuned to the ON position. When the selftest is completed, and no faults ae found, the lamp is tuned off. An indicato lamp that emains lit o comes on at any othe time duing vehicle opeation indicates a potential fault in the ABS. The ECU and the main connecto contol the ABS indicato lamp opeation. The ABS uses a seies of lamp flashes called blink codes to identify specific faults in the ABS. 1-30

System Opeation Pogess Check 1-2 Answe questions below befoe continuing to the next section. 1. The wheel speed senso is a positive pickup type senso. 2. ae electical signals sent to the ABS electonic contol unit. 3. If the ECU detemines that any wheels ae appoaching it contols the ABS modulato valve opeation to educe bake pessue. 4. When it is necessay to eapply the bake, both ABS valve solenoids ae. This etuns the system to the nomal bake application supply state. 5. The ECU and a contol the ABS indicato lamp opeation. 1-31

System Opeation Notes 1-32

Module 2 Diagnostics and Repai Table of Contents Definition of Tems.......................................2 Electonic Diagnostics Oveview...........................3 Blink Code Diagnostics and Fault Analysis.................11 Using MPSI Po-Link 9000................................25 Component Removal and Installation......................33 2-1

Module 2 Diagnostics and Repai Definition of Tems Active (Existing) Fault This type of fault epesents a failue in need of epai. An active fault causes the ABS indicato lamp to emain lit afte the ignition switch is tuned on. Examples of active faults ae senso cicuit failue, a boken wie o an inopeative ABS valve solenoid. Active fault codes must be epaied befoe they can be eased fom ECU memoy. Blink Code A two digit numbe that is stoed in ECU memoy and indicates a paticula cicuit o component failue. These codes can be accessed though the built-in ABS blink-code featue. The codes ae displayed as a set of two blink sequences fom the ABS indicato lamp. Blink Code Switch A switch that signals the ECU to activate blink code diagnostic capabilities. Switch types and locations vay, depending on the make and model of the vehicle. Diagnostic Datalink A vehicle datalink that is shaed by electonically contolled components on the vehicle like an electonic engine and the anti-lock baking system. The datalink allows you to connect an electonic sevice tool to the vehicle. Electonic Sevice Tool A device used to communicate with an electonic contol system. The tool has two diffeent functions: Accessing diagnostic infomation stoed in the systems memoy. Pefoming function tests on system components. Fault A component o cicuit malfunction that is detected by the ECU. The two types of faults, existing o intemittent, ae stoed fo etieval in the ECU. Fault Code A two digit numbe that is stoed in ECU memoy and indicates a paticula cicuit o component failue. Fault infomation can be accessed though the built-in ABS blink-code featue. An electonic diagnostic tool can also access the fault definition in non-code fom. This module will teach you how to use the appopiate Meito WABCO Maintenance Manual to intepet the fault codes and pefom elated pinpoint tests. Stoed (Intemittent) Fault Faults that affect ABS opeation only at cetain times. The ABS indicato lamp tuns on when a fault is fist detected. Howeve, if the vehicle is estated and the fault does not exist at that time, the ABS indicato lamp will then go out and the fault will be stoed in memoy. The ABS will function as nomal. An example of a stoed fault is a loose connecto. It is possible to ease stoed fault codes fom ECU memoy if the condition does not exist at that time. 2-2

Electonic Diagnostics Oveview Table of Contents Section Oveview........................................ 4 Electonic Diagnostic Methods............................ 5 Eo Detection and Response............................. 6 Eo Detection Methods............................. 6 Stat-Up Self-Test.................................... 6 Continuous Passive Monitoing....................... 6 Contol System Response to Eos..................... 7 Faults.............................................. 8 Section Summay........................................ 9 Pogess Check 2-1...................................... 10 2-3

Electonic Diagnostics Oveview Section Oveview As descibed ealie, ABS opeation entails a seies of inputs, pocessing and outputs. The wheel speed sensos povide inputs to the ECU. Afte pocessing (o intepeting) the inputs, the ECU issues commands (sends outputs). Then the ABS valves contol baking o the ATC valve contols taction. Faulty inputs, outputs o eactions to outputs can cause ABS malfunctions. Diagnosis involves detemining which of these is the cause of the poblem. Afte completing this section, technicians will be able to: Descibe how system eos ae detected and ecoded as fault codes. Explain how the ECU esponds to eos and how this affects ABS opeation. NOTE: View video tape segment numbe two. Retun to this wokbook when instucted to by the video tape and ead the est of Module Two. 2-4

Electonic Diagnostics Oveview Electonic Diagnostic Methods Thee ae two ways to diagnose ABS: Blink codes MPSI Po-Link 9000 sevice tool Onboad eo diagnosis is possible with the built-in ABS blink code featue. Blink code diagnostics can be pefomed without the use of any special diagnostic equipment. Meito WABCO ABS is also compatible with hand-held electonic sevice tools like the Po-Link 9000. A specific Meito WABCO ABS and ATC pogam catidge has been developed fo use with the Po-Link 9000. These diagnostic methods ae coveed in this module. But we will begin with a discussion of how the ABS contol system detects eos, how the system esponds to eos, and how eo infomation is stoed in the ECU. 2-5

Electonic Diagnostics Oveview ERROR DETECTION AND RESPONSE Eo Detection Methods Stat-Up Self-Test Continuous Passive Monitoing The development of the latest geneation of Meito WABCO ABS placed special emphasis on the electonic diagnostics of component failues. This esulted in a contol system opeation with distinct outines to detect system poblems: Stat-up self-test when the ignition is tuned on, which includes an active test of the ABS modulato valves Continuous passive monitoing within the ECU The ECU biefly tigges the ABS valves duing each ignition cycle. At the same time, it checks wheel speed sensos and othe essential ABS electonic components. It will then shut off the ABS indicato lamp if no failues ae found and if the wheel speed sensos wee in adjustment the last time the ignition was shut off. Note: If the gap between a senso and tooth wheel is too lage fo pope wheel-speed output duing low vehicle speeds, the indicato lamp will come on, even if nomal ABS opeation would be possible at highe vehicle speeds. Intenal electonic signal cicuits and components, such as input switching cicuits, compute and high-level signals also continually monito each othe fo failues and out-of-ange opeation. 2-6

Electonic Diagnostics Oveview Contol System Response to Eos The table below lists possible ABS system eos and esponses. Detected Eo Component o wiing failue Powe supply to ECU is inteupted o ABS connecto not plugged in. Individual electonic component fails intenally in the ECU. System Response to Eo ABS indicato lamp lights to infom vehicle opeato of the fault. Affected wheel(s) is emoved fom ABS contol and switched to nomal baking. The emaining ABS valves continue to povide ABS contol of baking. This povides seconday stability even fo full baking on a slippey oad suface. The eo type and how often it occus is stoed as a fault code in the ECU. This infomation can late be accessed by a technician, eithe though the blink code lamp o a diagnostic tool. ABS indicato lamp lights to infom vehicle opeato of the fault. All ABS and ATC systems would become inopeative. Nomal, non- ABS contolled baking would be available at all wheels. ABS indicato lamp lights to infom vehicle opeato of the fault. All o pat of the ABS is automatically shut off and that pat of the vehicle goes back to nomal baking. 2-7

Electonic Diagnostics Oveview Faults When the ABS electonic contol system detects a component o cicuit malfunction, the ECU will stoe a fault within its memoy. Thee ae two types of faults which can be detected: existing and stoed. An active fault is a cuent and continuous failue in need of epai. Active faults ae often called existing faults. Examples of active faults ae senso cicuit failue, a boken wie o an inopeative ABS valve solenoid. A stoed fault is a failue that affects ABS opeation only at cetain times. Stoed faults ae often called intemittent faults. An example of a stoed fault is a loose connecto. Faults ae stoed in memoy and etieved though eithe: Blink code system MPSI Po-Link 9000 Fault codes ae two-numbe combinations that indicate a paticula cicuit/component failue. 2-8

Electonic Diagnostics Oveview Section Summay This section povided an oveview of diagnostic capabilities built into the ABS electonic contol system. The following self-test outines wee descibed: Stat-up self-test Continuous passive monitoing within the ECU This section also povided an oveview of how the ECU esponds to eos, how eos affect ABS opeation, and how eos ae stoed in ECU memoy as fault codes. 2-9

Electonic Diagnostics Oveview Pogess Check 2-1 1. With each ignition cycle, the ECU biefly tigges the ABS. 2. If the total powe supply of the ECU is inteupted, all ABS and ATC systems become. 3. An active fault is a cuent o failue that needs epai. 2-10

Blink Code Diagnostics and Fault Analysis Table of Contents Oveview.............................................. 12 Blink Code Display..................................... 13 Blink Code Opeating Paametes......................... 13 Blink Code Pocedue................................... 14 Blink Code Cycle....................................... 14 Cleaing Faults fom ECU Memoy....................... 16 System Configuation Blink Code......................... 16 Cicuit Pinpoint Tests................................... 17 Pinpoint Test Pocedue................................. 18 Testing Resistance at Component......................... 18 Diagnostic Example..................................... 19 Section Summay....................................... 21 Pogess Check 2-2...................................... 22 2-11

Blink Code Diagnostics and Fault Analysis Oveview The blink code system allows you to identify fault codes stoed in the electonic contol unit memoy. This section will show you how to: Access stoed fault codes though the blink code switch and lamp Intepet fault codes. Clea fault codes fom the ECU memoy Check ABS system configuation 2-12

Blink Code Diagnostics and Fault Analysis Blink Code Display Blink Code Opeating Paametes With D vesion ABS, the blink code system uses the ABS indicato lamp to display blink codes. Befoe attempting to use the blink code featue, it is impotant to undestand its opeating paametes. When moe than one active fault is stoed in the ECU memoy, the fist active fault displayed must be coected befoe the next fault can be displayed. An active fault cannot be eased fom the ECU memoy until it is epaied. The blink code featue does not necessaily display the faults in the ode they wee ecoded by the ECU. Do not tun on the blink code featue switch while diving an ATC-equipped vehicle. Activating the switch may educe engine powe fo seveal seconds. Always pak the vehicle befoe tuning on the ABS blink code lamp. To pefom a blink code check, the vehicle's voltage system must be between 9.5 and 14 volts. 2-13

Blink Code Diagnostics and Fault Analysis Blink Code Pocedue Blink Code Cycle Follow these steps to access fault codes though the blink code featue: 1. Tun ignition to the ON position. 2. Pess and hold the blink code switch fo one second, then elease. 3. Recod numbe of blink code flashes (see Blink Code Cycle, below). 4. Afte ecoding both numbes of the fault code, tun the ignition switch to the OFF position. 5. Identify the ecoded blink code using the latest ABS Maintenance Manual. Afte activating the ABS blink code switch, the blink code cycle is as follows (efe to the illustations on the facing page): 1. The ABS indicato lamp will be lit while the switch is depessed. This is called the stat flash. It maks the beginning of the blink code sequence. 2. Afte eleasing the switch, thee is a 1.5 second pause. 3. ABS lamp flashes seveal times to indicate the fist numbe in the blink code sequence. 4. 1.5 second pause. 5. ABS lamp flashes seveal times to indicate the second numbe in the blink code sequence. 6. 4.0 second pause. 7. The blink code cycle keeps epeating fo an active fault code until the ignition switch is tuned OFF. 8. Fo stoed fault codes, each of the stoed codes ae displayed once and then the cycle stops. To epeat the stoed fault codes again, pess the blink code switch fo one second. If thee ae no faults in the ECU memoy, the displayed blink code will be 1-1. 2-14

Blink Code Diagnostics and Fault Analysis blah blah blahblah blah bl 1 Second Hold Light ON Pause 1.5 s Active Fault 1-8 Flashes Pause 1.5 s 1-6 Flashes Pause 4 s Pause 1.5 s 1st Digit 2nd Digit Repeat of Blink Code (2) (3) (2) (3) Continues until ignition is tuned off Blink Code 2-3 1 Second Hold Off Light ON Pause 1.5 s Stoed Faults (5) Pause 1.5 s Pause 4 s Pause 1.5 s 1st Digit 2nd Digit 1st Digit 2nd Digit 1st Stoed Fault 2nd Stoed Fault (2) (3) (4) Displays all stoed faults once last fault stoed is displayed fist Blink Codes 5-2 and 3-4 1 Second Hold System O.K. Light ON Pause 1.5 s Pause 1.5 s (1) (1) Blink Code 1-1: System OK S = Seconds Intepeting Blink Codes 2-15

Blink Code Diagnostics and Fault Analysis Cleaing Faults fom ECU Memoy Pess the blink code switch and hold it fo thee seconds, then elease. This will place the blink code system into the clea mode. The system will display eight quick flashes to indicate that the fault(s) was cleaed. This will be followed by the system configuation code, which will keep epeating until the ignition is shut off. If thee wee no quick flashes, then no fault codes have been eased. Note: Active fault codes must be epaied befoe they can be eased fom ECU memoy. Howeve, it is possible to ease stoed fault codes fom ECU memoy as long as the condition does not exist at that time. If you cannot clea a coected fault fom the ECU memoy, eithe the fault was not popely epaied o a poblem may exist within the ECU. Contact you Meito Distict Sevice Manage at 1-800-535-5560 in the U.S. o Canada. System Configuation Blink Code The ABS configuation is ecoded in the ECU. When in the fault code clea mode, the blink code system will display a system configuation code. This will occu whethe o not fault codes wee eased as indicated by the eight quick flashes. The configuation blink codes ae: One blink = 6 sensos/6 ABS modulato valves (6S/6M) Two blinks = 4 sensos/4 ABS modulato valves (4S/4M) Fou blinks = 6 sensos/4 ABS modulato valves (6S/4M) Veify that the configuation ecoded in the ECU and displayed by the blink code system matches the component configuation on the vehicle. 2-16

Blink Code Diagnostics and Fault Analysis blah blah blah 3 Second Hold Light ON Pause 1.5 s Faults Cleaed Pause 4 s Note: Afte faults ae cleaed and vehicle is stated, ABS lamp will stay on until vehicle is diven ove 4 mph (6 km/h). 8 Quick Blinks = Faults Cleaed System ID System ID System ID System ID (2) (2) (2) (2) Pause 4 s Pause 4 s Pause 4 s Continues until ignition is tuned off System Configuation Code 2: 4S/4M System 3 Second Hold Light ON Pause 4 s Faults Not Cleaed (Active Faults Still Exist) Pause 4 s Pause 4 s Pause 4 s System ID System ID System ID System ID (2) (2) (2) (2) Continues until ignition is tuned off S = Seconds Cleaing Fault Codes 2-17

Blink Code Diagnostics and Fault Analysis Cicuit Pinpoint Tests Although they can identify faulty components and povide elated geneal infomation, electonic diagnostics cannot identify the exact location of a cicuit failue. To do this, the technician must use a digital multimete (DMM) to pefom pinpoint tests on the vaious wiing haness connectos. Once a fault has been identified in a specific cicuit (example: open cicuit at the ight font senso), it will be necessay to find the exact location in the cicuit whee the fault is. The fault may eithe be in a section of the wiing haness o it could be in the component at the end of the haness. To find the location of the fault, stat with the connecto at the ECU that contains the faulty cicuit and do a esistance o voltage test with a DMM. The latest ABS Maintenance Manual povides ECU connecto end-view diagams as well as voltage and esistance specifications fo ABS cicuits and components. If the complete cicuit checks to specification, then the fault may be inside the ECU. If the cicuit does not meet specifications, find the next connecto in the wiing haness of the faulty cicuit and check voltage o esistance at this point. Continue to check down the cicuit until the component is eached. Pefom the appopiate test on the component. This should identify if the component o cicuit wiing is faulty. Note: Be caeful to pevent damaging electical teminals and haness connectos while toubleshooting and testing the ABS system. 2-18

Blink Code Diagnostics and Fault Analysis Pinpoint Test Pocedue Testing Resistance at Component Use the following pocedue to pefom pinpoint tests on ECU haness connectos. 1. Detemine the faulty cicuit though blink code o electonic diagnostic tool. 2. Tun the ignition key to the OFF position. 3. Disconnect the connecto on the ECU that contains the fault cicuit. 4. Consult the latest ABS Maintenance Manual to detemine the connecto and pins to test and the coect mete setting. 5. Set the digital multimete to the appopiate scale. 6. Touch the multimete pobes to the designated teminals on the ECU haness connecto. 7. Compae the multimete eading to specified values in the ABS Maintenance Manual. 8. Repai o eplace wiing o component as necessay. 9. Reconnect the haness connectos to the ECU. 10. Use the ABS indicato lamp featue, and if necessay, oad test the vehicle to veify that the ABS system is functional. In ode to isolate the location of a fault, pinpoint tests can be pefomed on the component suspected to be faulty. Resistance can be measued acoss the ABS valve solenoid connecto teminals. When measued between the common pin (pin 1) and eithe of the solenoid pins (pins 2 o 3), the esistance should be between 4 and 8 ohms. Wheel-speed senso esistance can also be measued diectly at the senso connecto when it is disconnected fom the chassis haness. Wheel-speed senso esistance should be between 500 and 2000 ohms. 2-19

Blink Code Diagnostics and Fault Analysis Diagnostic Example A dive epots that his vehicle s ABS lamp came on and stayed on duing his last tip. A technician activates the blink code system and etieves active fault code 3-5. The technician consults the latest Maintenance Manual to detemine whee the fault is located. The Blink Code Identification chat identifies the fault as: Too much senso gap in the ight ea/ea tandem dive axle (cub side). Fo this fault, the ABS Maintenance Manual instucts the technician to adjust the senso by pushing it in until it contacts the tooth wheel, then check senso voltage. 2-20

Blink Code Diagnostics and Fault Analysis Diagnostic Example (Cont.) This vehicle has a cab-mounted ECU. Theefoe, the voltage check is pefomed at pins 8 and 9 of the 15-pin ECU haness connecto. Cab-Mounted ECU Connecto Senso Pin Locations ECU Senso Connecto Pins Cab-Mounted LF 6-Pin 4 and 5 RF 9-Pin 4 and 5 LR 15-Pin 5 and 6 RR 15-Pin 8 and 9 If the vehicle had a fame-mounted ECU, the voltage check would be pefomed on pins 3 and 4 of the geen connecto. Fame-Mounted ECU Connecto Senso Pin Locations ECU Senso Connecto Pins Fame-Mounted LF X2 Black 7 and 8 RF X2 Black 5 and 6 LR X3 Geen 1 and 2 RR X3 Geen 3 and 4 When pefoming a senso voltage check, the wheel fo that senso must be spun at a speed of 30 pm o moe. The voltage should be at least 0.200 volt AC. A voltage eading below this would usually indicate too lage of a gap between the senso and the tooth wheel. 2-21

Blink Code Diagnostics and Fault Analysis Section Summay This section povided the following infomation: The blink code lamp flashes to display a two-digit code epesenting an active o stoed fault code, ecoded by the ECU. Blink codes ae displayed by tuning the ignition key to the ON position and pessing the blink code switch fo one second. Afte getting the blink code, efe to the latest ABS Maintenance Manual to detemine what the fault code means and the pope actions to be taken to coect the fault. Blink codes ae cleaed fom the ECU memoy by holding down the blink code switch fo at least thee seconds. Active faults can only be eased if the cause of the fault has been coected. Stoed faults can be eased at any time. The pocedue used to clea a fault can also be used to check if the ABS configuation ecoded in the ECU matches the component configuation on the vehicle. 2-22

Blink Code Diagnostics and Fault Analysis Pogess Check 2-2 Answe the questions below befoe continuing to the next section. 1. The blink code cycle is epeated fo an active fault code until the switch is tuned OFF. 2. If thee ae no faults in the ECU memoy, the system will display code -. 3. If you cannot ease a coected fault fom the ECU memoy, eithe the fault was not popely epaied o a poblem may exist within the. 4. Diagnostic pinpoint tests on the ECU connectos should be pefomed with the ignition key in the position. 2-23

Blink Code Diagnostics and Fault Analysis Notes 2-24

Using MPSI Po-Link 9000 Table of Contents Oveview............................................... 26 MPSI Po-Link 9000 Components.......................... 27 Using the Po-Link 9000.................................. 28 Stat-Up Pocedue.................................. 28 Po-Link Functions.................................. 28 Component Tests.................................... 29 System Setup........................................ 30 Section Summay........................................ 31 Pogess Check 2-3....................................... 32 2-25

Using MPSI Po-Link 9000 Oveview The MPSI Po-Link 9000 is a micopocesso-based diagnostic tool designed to communicate with the ECU. It is pogammed to povide ead-outs that can be used fo diagnostics. Technicians can use the diagnostic tool to: Access existing and intemittent faults stoed in ECU memoy. These faults identify faulty cicuits/components. Pefom functional tests on ABS/ATC components. 2-26

Using MPSI Po-Link 9000 MPSI Po-Link 9000 Components The MPSI Po-Link 9000 hand-held diagnostic tool includes: Cables and adaptes needed to inteface with the ABS contol system diagnostic connecto. Data catidge (vesion 4.0 o highe) designed specifically fo Meito WABCO ABS systems. Read-out window fo infomation display. 16-key keypad fo enteing commands and infomation into the Po-Link 9000 and the ABS ECU. Po-Link 9000 use s manual. 15 PIN VEHICLE CABLE DATA CABLE ADAPTER DATA CARTRIDGE Po-Link 9000 Electonic Sevice Tool Components 2-27

Using MPSI Po-Link 9000 USING THE PRO-LINK 9000 Stat-Up Pocedue Follow the instuctions in the use s manual of the Po-Link 9000 fo connecting the Po-Link to the vehicle diagnostic datalink. This is usually the same connecto inside the cab that is used to toubleshoot the electonic engine contol module. Po-Link Functions Thee ae seven majo functions that can be pefomed using the Po-Link 9000: Existing Fault This function povides desciptions of the existing faults ecoded in the ECU memoy. Stoed Fault This function povides desciptions of the stoed (intemittent) faults ecoded in the ECU memoy. Pogam ID This function povides infomation about the ECU, including the softwae vesion numbe, ECU pat numbe and ECU build date. Component Tests This function allows you to test a vaiety of ABS and ATC components. The available tests ae descibed on the following pages. System Setup This function allows you to configue the Po- Link tool to match the vehicle s ABS component configuation. RS-232 Seial Pot This selection allows you to configue the seial pot on the Po-Link fo use with a pinte o pesonal compute. Contast Adjust The Po-Link display sceen contast can be adjusted eithe lighte o dake though this function. Consult Po-Link 9000 use s manual fo moe infomation on accessing and using these functions. 2-28

Using MPSI Po-Link 9000 Component Tests This function allows uses to test a vaiety of ABS cicuits and components. This includes continuity checks and component actuation (opeation). The following Tacto Component Test selections ae available: Vehicle Voltages This test enables the technician to monito the two voltage signals poweing the ECU fo each diagonal. On the D-basic ABS vesion only one voltage is monitoed. ABS Valves In this test, the ECU individually activates each ABS valve. It does this by sending a pogammed seies of 12-volt signals to the ABS valve that is being tested. ABS/ATC Lamps This test allows the technician to monito the status of the ABS and ATC indicato lamps on the dash panel. Sensos This test monitos inputs fom each wheel senso to the ECU. ABS/ATC Switches This test allows the technician to monito the states of the ABS/ATC switches on the instument panel o ABS fuse/elay panel. Retade Datalink With an electonic etade contolled by the engine ECM, and a popely installed J1922 datalink, this test will check that the etade can be disabled by ABS ECU and engine ECM. Retade Relay When this test is activated, the etade elay is enegized and the contacts opened. This ceates an open cicuit in the etade switch cicuit, theeby shutting off the etade. Thee ae also seveal tests available fo taile ABS systems. Consult the Po-Link use s manual fo moe infomation on taile system diagnostics. 2-29

Using MPSI Po-Link 9000 System Setup System Setup is used to configue the Po-Link tool to match ABS configuation being woked on. Available configuation options ae: 4 Sensos/4 Valves 6 Sensos/4 Valves 6 Sensos/6 Valves 2-30

Using MPSI Po-Link 9000 Section Summay This section povided the following infomation: The Po-Link 9000 diagnostic tool can be used to: Access existing and stoed faults in the ECU memoy Pefom functional tests on ABS/ATC components Change diagnostic o system configuation and paametes The Po-Link allows technicians to pefom the following functions: Access existing faults Access stoed faults View Pogam ID infomation Check the voltage poweing the ECU Pefom tests on the ABS valves, ATC valve, ABS/ATC lamps, sensos, engine datalink, etade elay, etade datalink and ABS/ATC switches. 2-31

Using MPSI Po-Link 9000 Pogess Check 2-3 Answe the questions below befoe continuing to the next section. 1. The Engine Datalink test detemines if the system is capable of communicating with the electonic engine contol system. 2. The ECU pat numbe is displayed on the Po-Link sceen. 2-32

Component Removal and Installation Table of Contents Safety Wanings......................................... 34 Font Wheel Speed Senso Replacement.................... 35 Removing.......................................... 35 Installing........................................... 35 Rea Wheel Speed Senso Replacement..................... 36 Removing.......................................... 36 Installing........................................... 36 ABS Valve Replacement.................................. 38 Removing.......................................... 38 Installing........................................... 38 Checking Installation................................. 38 Road Test............................................... 39 Pogess Check 2-4....................................... 40 2-33

Component Removal and Installation Safety Wanings Always obseve the following safety ules wheneve woking on a vehicle. Apply the paking bake and place blocks unde the ties. Do not wok on a vehicle suppoted only by jacks. Jacks can slip o fall ove and cause seious pesonal injuy. Always use safety stands. To pevent seious eye injuy, always wea safe eye potection when pefoming maintenance o sevice. Adhee to you shop s nomal safety pactices. Always consult the appopiate Meito WABCO maintenance manuals befoe pefoming any wok. Follow all wanings and cautions povided in the maintenance manuals. 2-34

Component Removal and Installation Font Wheel Speed Senso Replacement Removing 1. Place blocks unde the ea ties to stop the vehicle fom moving. Raise the font of the vehicle until the ties ae off the gound. Place safety stands unde the axle. 2. Use a twisting motion to emove the senso fom the steeing knuckle. Do not pull on the senso cable. Font Wheel Speed Senso 3. Disconnect the fastenes that hold the senso cable to othe components 4. Disconnect the senso cable fom the chassis haness. 5. Remove the senso sping clip fom the bushing in the steeing knuckle. Installing 1. Connect the senso cable to the chassis haness. 2. Install the fastenes that hold the senso cable in place. 3. Apply a mineal oil-based lubicant that contains molydisulfide to the senso sping clip and body of the senso. Use a lubicant that has excellent anti-coosion and adhesion chaacteistics and is capable of continuous function in a tempeatue ange of -40 to 300 F (-40 to 149 C). 4. Install the senso sping clip into the bushing in the steeing knuckle. The sping clip must be installed with the flange stops on the inboad side of the vehicle. 5. Push the senso completely into the senso sping clip until it contacts the tooth wheel. If the hub is not yet installed, push the senso all the way into its holde. 6. Remove blocks and safety stands. 2-35

Component Removal and Installation Rea Wheel Speed Senso Replacement Removing 1. Place blocks unde the font ties to stop the vehicle fom moving. 2. Raise the ea of the vehicle until the ties ae off the gound. 3. Place safety stands unde the axle. 4. Release the paking bake. 5. Remove the wheel and tie assembly fom the axle. 6. Remove the bake dum. It may be necessay to back off the slack adjuste befoe emoving the dum. 7. Use a twisting motion to emove the senso fom the mounting block in the axle housing. Do not pull on the senso cable. 8. Remove the senso sping clip fom the mounting block. 9. Disconnect the fastenes that hold the senso cable to othe components. 10. Disconnect the senso cable fom the chassis haness. Installing 1. Apply a mineal oil-based lubicant that contains molydisulfide to the senso sping clip and body of the senso. Use a lubicant that has excellent anti-coosion and adhesion chaacteistics and is capable of continuous function in a tempeatue ange of -40 to 300 F (-40 to 149 C). 2. Install the senso sping clip into the mounting block. The sping clip must be installed with the flange stops on the inboad side of the wheel end. 3. Push the senso completely into the senso sping clip until it contacts the tooth wheel. If the hub is not yet installed, push the senso all the way into its holde. 2-36

Component Removal and Installation Rea Wheel Speed Senso Replacement 4. Inset the senso cable though the hole in the spide and axle housing flange. Route the cable to the fame ail. Be sue to oute the cable in a way that pevents pinching o chaffing, and allows fo sufficient movement fo suspension tavel. SPRING CLIP SENSOR HOLDER SENSOR SPRING CLIP TAB Rea Wheel Speed Senso 5. Connect the senso cable to the chassis haness. 6. Install the fastenes that hold the senso cable in place. 7. Install the bake dum on the wheel hub. 8. Adjust the ea bakes. 9. Install wheel and tie assembly on the axle. 10. Remove blocks and safety stands fom font ties. 2-37

Component Removal and Installation ABS Valve Replacement Removing 1. Disconnect the haness connecto fom the ABS valve. 2. Disconnect the ai supply line fom ABS valve pot 1 and disconnect the ai delivey line fom pot 2. 3. Remove the two mounting capscews and nuts. 4. Remove the ABS valve. Installing 1. Install the ABS valve with two mounting capscews and nuts. Tighten the capscews to 18 lb-ft (24 N m). 2. Connect the delivey line (fom bake chambe) to ABS valve pot 2 and connect the ai supply line to pot 1. 3. Connect the haness connecto to the ABS valve. 4. Remove the blocks fom the font and ea ties. Checking Installation ABS Valve 1. Apply the bakes. Listen fo leaks at the modulato valve. 2. Tun the ignition on and listen to the modulato valve cycle. If the valve fails to cycle: Check the electical connection. Check fo fault codes. 3. Dive the vehicle. Veify that the ABS indicato lamp opeates popely. 2-38

Component Removal and Installation Road Test Always oad test the vehicle afte epaiing o sevicing the ABS o ATC system. The pocedue is: 1. Make sue all of the haness connectos ae secuely attached to the ECU. 2. Check that all senso, ABS valve and ATC valve connectos ae secuely attached. 3. Tun the ignition switch to the ON position. 4. Note whethe the ABS indicato lamp functions popely. 5. If the ABS indicato lamp emains on, echeck fo faults. 6. Ease any faults found. 7. Recycle the ignition switch and check fo faults again. 8. If the senso has been eplaced o eadjusted, it will be necessay to test dive the vehicle to make sue that the senso is popely adjusted. If the ABS lamp comes on duing the test dive, check fo faults. 2-39

Component Removal and Installation Pogess Check 2-4 Answe questions below befoe continuing to the next section. 1. When installing a wheel speed senso, the sping clip must be installed with the flange stops on the side of the wheel end. 2. Use a motion to emove the wheel speed senso fom the steeing knuckle o mounting block. 3. When installing a ea wheel speed senso, inset the senso cable though the hole in the and axle housing flange. 2-40

Module 3 ATC Opeation, Diagnostics and Repai Table of Contents ATC Components and System Opeation................... 3 ATC Diagnostics....................................... 15 Component Removal and Installation..................... 23 3-1

Module 3 ATC Opeation, Diagnostics and Repai Definition of Tems Active (Existing) Fault This type of fault epesents a failue in need of epai. An active fault causes the ABS indicato lamp to stay lit when the ignition is tuned on. Examples of active faults ae senso cicuit failue, boken wie o an inopeative ABS valve solenoid. Active fault codes must be epaied befoe they can be eased fom ECU memoy. ATC Indicato Lamp On ATC equipped vehicles, an ATC (may also be labelled ASR o WHEEL SPIN) indicato lamp is located on the vehicle instument panel. The lamp is lit wheneve the dive wheels ae spinning. ATC Valve A solenoid contolled on/off ai valve that povides ai pessue fo taction contol applications. Blink Code A two digit numbe that is stoed in ECU memoy and indicates a paticula cicuit o component failue. These codes can be accessed though the built-in ABS blink-code featue. The codes ae displayed as a set of two blink sequences fom the ABS indicato lamp. Blink Code Switch A switch that signals the ECU to activate blink code diagnostic capabilities. Switch types and locations vay, depending on the make and model of the vehicle. DEEP SNOW/MUD Switch The optional DEEP SNOW/MUD switch is located on the instument panel of vehicles equipped with ATC. When the switch is in the DEEP SNOW/MUD position it signals the ECU to allow moe wheel spin than nomal. Diagnostic Datalink A vehicle datalink that is shaed by electonically contolled systems on the vehicle like an electonic engine and the anti-lock baking system. The datalink allows an electonic sevice tool to communicate with the ECU of the electonically contolled system. Diffeential Baking The pimay ATC contol function when dive wheels ae opeating on diffeent sufaces (e.g., one wheel on ice, the othe wheel on dy pavement). Diffeential baking automatically contols the dive wheel(s) on one side of the vehicle when the ECU senses those wheels spinning. This tansfes engine powe to the wheels on the opposite side. 3-2

Module 3 ATC Opeation, Diagnostics and Repai Definition of Tems (Cont d) Electonic Engine Contol The pocess by which the ABS contols the engine when the dive wheels ae spinning. When the ECU detects that diving wheels on both sides of the vehicle ae beginning to slip, it automatically signals the engine s Electonic Contol Module (ECM), though the J1922/J1939 datalink, to educe engine toque. Fault A component o cicuit malfunction that is detected by the ECU. The two types of faults, existing o intemittent, ae stoed fo etieval in the ECU. Stoed Fault (Intemittent) Faults that affect ABS opeation only at cetain times. The ABS indicato lamp tuns on when an intemittent fault is detected, but the lamp may not come back on afte the ignition switch is ecycled. An example of intemittent fault is a loose connecto. It is possible to ease stoed fault codes fom ECU memoy, only if the condition does not exist at that time. 3-3

Module 3 ATC Opeation, Diagnostics and Repai Notes 3-4

ATC Components and System Opeation Table of Contents Section Oveview......................................... 6 Automatic Taction Contol (ATC) Oveview................. 7 ATC Opeation Summay.............................. 7 ATC Featues and Benefits............................. 7 Electonic Contol Unit (ECU) ATC Opeation............ 8 ATC Components........................................ 9 ATC Solenoid Valve Opeation......................... 9 ATC Solenoid Valve Location......................... 10 SAE J1922/J1939 Data Link........................... 11 ATC Indicato Lamp................................. 11 DEEP SNOW/MUD Switch........................... 11 Section Summay........................................ 12 Pogess Check 3-1....................................... 13 3-5

ATC Components and System Opeation Section Oveview This section intoduces Automatic Taction Contol (ATC) which is an option that can be added to the ABS. ATC components and thei functions ae discussed. Specific featues and benefits of the Meito WABCO ATC system ae pesented as well. Afte completing this section, the technician will be able to: Descibe the basic functions of the Meito WABCO Automatic Taction Contol (ATC). Locate the ATC valve. Undestand how the ATC indicato lamp functions. Undestand the use of the DEEP SNOW/MUD switch. NOTE: View video tape segment numbe thee. Retun to this wokbook when instucted to by the video tape and ead the est of Module Thee. 3-6

ATC Components and System Opeation AUTOMATIC TRACTION CONTROL (ATC) OVERVIEW ATC Opeation Summay Automatic Taction Contol (ATC) is available as an option with Meito WABCO ABS. ATC uses many of the same components as the ABS system to contol wheel spin, theeby impoving taction and vehicle stability. Two functions accomplish this: Diffeential Baking: When a dive wheel on one side of the vehicle begins to spin, ATC automatically applies the bakes to the wheels on that side. This tansfes engine powe to the othe diving wheels. Diffeential baking is the pimay contol when dive wheels ae opeating on diffeent sufaces (fo example, one wheel on ice, the othe wheel on dy pavement). Electonic Engine Contol: If dive wheels on both sides of the vehicle begin to slip, ATC automatically educes engine toque to egain taction. The ATC signal to the electonic engine oveides the pedal command fom the dive in ode to contol wheel spin. ATC, just like ABS, woks automatically. Dives do not have to select this featue. An ATC indicato lamp will come on to infom the dive that a wheel is spinning and the ATC system is functioning. ATC Featues and Benefits Featues Diffeential baking and electonic engine contol ATC indicato lamp DEEP SNOW/MUD switch (optional) Benefits Impoved taction on slippey sufaces. Reduced potential of poweing into a jackknife caused by wheel ovespin duing acceleation o on cuves. Impoved tie life. Wans vehicle opeato that a dive wheel is spinning. Allows fo inceased wheel spin on soft sufaces like snow o mud. 3-7

ATC Components and System Opeation Electonic Contol Unit (ECU) ATC Opeation To detemine if a dive wheel is stating to spin, the ECU compaes the speed of the dive wheels to the font axle wheel speeds. If the dive wheels on one o both sides of the vehicle ae spinning faste than the font wheels, the ECU will activate the ATC system to contol the spin. At the same time, the ECU will light the ATC indicato lamp. If wheel speed senso signals indicate that a wheel on one side of the vehicle is spinning, the ECU signals the ATC valve to povide ai pessue to open the elay valve. The appopiate ABS modulato valve then contols baking on the spinning wheel(s). The inlet solenoid of the ABS modulato valve fo the opposite side is activated by the ECU to block ai fom enteing the bakes on the non-spinning side of the vehicle. Baking the dive wheel(s) on one side of the vehicle tansfes toque to the wheel(s) on the opposite side. This pocess is called diffeential baking. Diffeential baking is the pimay contol function when dive wheels ae opeating on diffeent sufaces (one wheel on ice, the othe wheel on dy pavement). If wheel speed senso signals indicate that wheels on both sides of the vehicle ae spinning, the ECU will send a signal to the engine s electonic contol module by way of the J1922/J1939 datalink. The electonic contol module will then educe engine toque to contol wheel spin. Note: On tandem axle vehicles with 4S/4M ABS, only the wheels on one dive axle have sensos. If a wheel without a senso stats spinning, the ATC system is not awae of it and will not espond. As always, when on slippey oads, the dive should have the inte-axle diffeential (IAD) locked. 3-8

ATC Components and System Opeation ATC COMPONENTS ATC Solenoid Valve Opeation The ATC solenoid valve is a solenoid-contolled on/off ai valve that contols ai pessue to the signal line of the elay valve. When a wheel speed senso signals that the wheel(s) on just one side of the vehicle is spinning, the Electonic Contol Unit (ECU) signals the ATC valve to open, which povides ai pessue into the signal line of the elay valve. This opens the elay valve, supplying ai to ABS modulato valves. The ECU then contols the appopiate ABS modulato valve(s) to bake the wheel(s) on the side that is spinning. Fo the side that is not spinning, the ECU signals the ABS modulato valve to close the inlet pot. This blocks the ai fom getting to the bake chambes on that side of the vehicle. Baking the dive wheel(s) on one side of vehicle automatically supplies moe toque to the dive wheel(s) on the othe side that is not slipping. This function is called diffeential baking. ATC Valve 3-9

ATC Components and System Opeation ATC Solenoid Valve Location The ATC valve has two possible mounting locations: When an ABS valve package is used, the ATC valve may be attached to the elay valve). ATC VALVE SUPPLY LINE FOOT VALVE CONTROL LINE DELIVERY LINES ABS Valve Package with ATC Valve When used with an ABS system with individual ABS modulato valves, the ATC valve is mounted on the vehicle fame o a cossmembe. CONTROL LINE SUPPLY LINE ATC VALVE FOOT VALVE CONTROL Individual ATC Valve 3-10

ATC Components and System Opeation SAE J1922/J1939 Data Link ATC Indicato Lamp The SAE J1922/J1939 data link is a cicuit consisting of a twisted pai of wies that allows communication between the ABS ECU and the engine s Electonic Contol Module (ECM). When the ABS ECU detemines that wheels on both sides of the vehicle ae spinning, it sends a signal ove the SAE J1922/J1939 data link to the engine ECM. The engine ECM then educes engine toque to contol wheel spin. In this situation, the ATC signal fom the ABS ECU oveides the pedal command fom the dive. Note: The SAE J1922/J1939 data link must be disabled befoe testing a vehicle equipped with ATC on a Dynamomete. This can be accomplished using the blink code switch, and is explained late in this module. On ATC-equipped vehicles, an ATC (may also be labelled ASR o WHEEL SPIN) indicato lamp is located on the vehicle instument panel. The lamp is lit wheneve the dive wheels ae spinning. If the lamp stays on duing nomal vehicle opeation, thee may be a malfunction in the ATC system. Some vehicles without ATC may have a wheel spin lamp to indicate to the dive that the wheels ae spinning. DEEP SNOW/MUD Switch The optional DEEP SNOW/MUD switch is located on the instument panel of vehicles equipped with ATC. The dive should activate the DEEP SNOW/MUD switch in deep snow o off-oad situations. This signals the ECU to allow moe wheel spin than nomal. The ATC (wheel spin) lamp blinks continuously when this switch is in the DEEP SNOW/MUD position. The switch should be etuned to the NORMAL position when the vehicle is no longe in deep snow o mud. The lamp will then stop blinking. 3-11

ATC Components and System Opeation Section Summay This section povided the following infomation: The ECU monitos the wheel speed senso signals to detemine if dive wheels ae spinning. The ECU contols taction by eithe: Diffeential baking, which bakes the spinning wheel(s) and tansfes toque to the wheel(s) on the opposite side. Electonic engine contol, which educes engine powe when wheels on both sides of the vehicle ae spinning. Duing ATC opeation, the ATC solenoid valve supplies ai pessue into the signal line of the elay valve. This opens the elay valve, supplying ai to the ABS modulato valves. The ECU then contols the appopiate ABS modulato valve to povide baking on the spinning dive wheel(s). The ATC lamp comes on and stays on if the ATC system activates. It goes off when wheels have stopped spinning. The lamp blinks when the ATC switch is in the DEEP SNOW/MUD position. The optional ATC DEEP SNOW/MUD switch is used to allow moe wheel spin in deep snow o off-oad conditions. 3-12

ATC Components and System Opeation Pogess Check 3-1 Answe the questions below befoe continuing to the next section. 1. The pimay ATC contol function when dive wheels on only one side of the vehicle ae spinning is baking. 2. Unde most conditions, the DEEP SNOW/MUD switch should be in the position. 3. If wheels on both sides of the vehicle begin to slip, the ATC automatically educes engine to egain taction. 4. Duing ATC diffeential baking, the ABS Electonic Contol Unit (ECU) causes the ATC valve to povide ai pessue to the ABS fo the spinning dive wheel(s). 5. The SAE J1922/J1939 data link is a cicuit consisting of a pai of wies. 3-13

ATC Components and System Opeation Notes 3-14

ATC Diagnostics Table of Contents Section Oveview........................................ 16 Blink Code Diagnostics................................... 17 Dynamomete Testing of Vehicles with ATC................ 17 ATC Valve Pinpoint Test................................. 18 MPSI Po-Link 9000...................................... 19 Component Tests........................................ 19 Section Summay........................................ 20 Pogess Check 3-2....................................... 21 3-15

ATC Diagnostics Section Oveview As discussed in modules 2 and 3, thee ae two ways to diagnose ABS/ATC systems: Blink codes MPSI Po-Link 9000 This section will demonstate how to use both methods to identify ATC faults. Instuction will also be povided on using a digital multimete (DMM) to pefom pinpoint tests on the ECU haness and ATC valve connectos. 3-16

ATC Diagnostics Blink Code Diagnostics Dynamomete Testing of Vehicles with ATC The blink code system allows you to identify fault codes stoed in the electonic contol unit memoy. Refe to modules 2 and 3 fo instuction on accessing and intepeting blink codes. The ATC must be disabled befoe an ATC-equipped vehicle can be tested on a dynamomete. To do this, pess and hold the blink code switch fo at least thee seconds. This will place the blink code system into the configuation mode which disables the ATC. The ATC lamp will be lit while the ATC system is disabled. Note: If all faults ae cleaed, the blink code lamp will flash eight times befoe it entes the configuation mode. If faults ae pesent, the blink code lamp will immediately ente the configuation mode. 3-17

ATC Diagnostics ATC Valve Pinpoint Test In ode to find the location of a fault, tests can be pefomed on the component suspected to be faulty. Resistance can be measued acoss the ATC valve solenoid connecto teminals. Resistance should be between 8 and 14 ohms. ATC Valve Solenoid Pins If the esistance is geate than 14 ohms, clean the electical contacts and check the esistance again. To check the cable and ATC valve esistance as one unit, measue esistance acoss the pins on the ECU connecto haness as called out in the ABS Maintenance Manual. 3-18

ATC Diagnostics MPSI Po-Link 9000 Component Tests Module 2 descibed how to use the MPSI Po-Link 9000 handheld electonic sevice tools to diagnose ABS faults. ATC diagnostics is accomplished in the same manne. Also efe to the Po-Link 9000 use s manual fo moe infomation. The Po-Link 9000 is also capable of pefoming tests on ATC cicuits and components. This includes cicuit checks and component actuation (opeation). ATC Valve In this test, the ECU activates the ATC valve. Duing the test, the ECU will apidly fie the valve seveal times. Duing this test, listen to veify that the ATC valve is functioning. ABS/ATC Lamps This test allows the technician to monito the state of the ABS and ATC indicato lamps on the instument panel. Engine Datalink This test detemines if the ATC is communicating with the electonic engine contol system. With the engine unning at appoximately 1000 RPM, thee should be a dop in engine RPM duing this test. ABS/ATC Switches This test allows the technician to check the ABS/ATC switches (if installed) on the instument panel o ABS fuse/elay panel. 3-19

ATC Diagnostics Section Summay This section povided the following infomation: ATC faults can also be displayed using the blink code system. The MPSI Po-Link 9000 electonic sevice tool can also be used to display ATC system faults and to pefom the following ATC component test: ATC Valve ABS/ATC Lamps Engine Datalink ABS/ATC Switches ATC valve esistance can be measued at eithe the ECU haness connecto o the valve connecto. Befoe testing a vehicle with ATC on a dynamomete, the ATC function must be disabled using the blink code switch. 3-20

ATC Diagnostics Pogess Check 3-2 Answe the questions below befoe continuing to the next section. 1. The ATC function must be disabled befoe testing a vehicle on a. 2. Resistance measued acoss the ATC valve solenoid connecto teminals should be should be between and ohms. 3-21

ATC Diagnostics Notes 3-22

Component Removal and Installation Table of Contents Safety Wanings......................................... 24 ATC Valve Replacement (Individually Mounted)............ 25 Removing.......................................... 25 Installing........................................... 26 ATC Valve Replacement (ABS Valve Package)............... 27 Removing.......................................... 27 Installing........................................... 28 Checking ATC Valve Installation.......................... 29 Pogess Check 3-3....................................... 30 3-23

Component Removal and Installation Safety Wanings Always obseve the following safety ules wheneve woking on a vehicle. Apply the paking bake and place blocks unde the ties. Do not wok on a vehicle suppoted only by jacks. Jacks can slip o fall ove and cause seious pesonal injuy. Always use safety stands. To pevent seious eye injuy, always wea safe eye potection when pefoming maintenance o sevice. Adhee to you shop s nomal safety pactices. Always consult the appopiate Meito WABCO maintenance manuals befoe pefoming any wok. Follow all wanings and cautions povided in the maintenance manuals. 3-24

Component Removal and Installation ATC Valve Replacement (Individually Mounted) Removing 1. Tun the ignition switch to the OFF position 2. Block the font and ea ties. Raise the vehicle, if necessay. 3. Bleed ai pessue fom the supply esevoi that feeds the ATC valve. 4. Disconnect the haness connecto fom the ATC valve. 5. Disconnect the ai supply line fom ATC valve pot 1, the contol line fom pot 2 and the foot valve contol line fom pot 3. CONTROL LINE TO RELAY VALVE PORT 1 (AIR SUPPLY FROM RESERVOIR) PORT 2 VALVE CONTROL DO NOT OPEN PORT 3 FOOT VALVE CONTROL LINE 6. Remove the two mounting capscews, washes and nuts. CAPSCREWS 7. Remove the ATC valve. 3-25

Component Removal and Installation ATC Valve Replacement (Individually Mounted) (Cont.) Installing 1. Install the ATC valve with two mounting capscews, washes and nuts. Tighten the capscews pe the manufactue s specifications. 2. Connect the ai supply line to pot 1, the contol line to pot 2 and the foot valve contol line to pot 3. 3. Connect the haness connecto to the ATC valve. Hand tighten only. 4. Lowe the vehicle if it has been aised and emove the blocks. 5. Test the installation. 3-26

Component Removal and Installation ATC Valve Replacement (ABS Valve Package) Removing Note: If thee is enough oom to wok, it is not necessay to emove the valve package fom the vehicle befoe eplacing the ATC valve. 1. Tun the ignition switch to the OFF position. 2. Block the font and ea ties. Raise the vehicle, if necessay. 3. Bleed ai pessue fom the supply tank that feeds the valve. 4. Disconnect the haness connecto fom the ATC valve. 5. Disconnect the ai supply line fom the supply pot on the adapte. 6. Disconnect the foot valve contol line fom the ATC valve. 7. Use a 5 mm Allen wench to emove the two scews that hold the adapte to the elay valve potion of the valve package. 8. Use a 6 mm Allen wench to emove the two mounting bolts that hold the ATC valve to the adapte. 9. Remove the ATC valve fom the adapte. 10. Remove the adapte, seal and O-ing fom the valve package. MOUNTING BOLTS ATC VALVE ADAPTER O-RINGS FOOT VALVE CONTROL LINE SEAL SUPPLY AIR LINE 3-27

Component Removal and Installation ATC Valve Replacement (ABS Valve Package) (Cont.) Installing Note: When installing the new ATC valve on the valve package, you must use new O-ings, seal, mounting bolts, and lubicant included with the eplacement kit. 1. Clean and lubicate the small adapte O-ing and install the O-ing on the adapte. 2. Use two new bolts to attach the ATC valve to the adapte. 3. Lubicate the eplacement seal and install it in pot 2 of the ATC valve. 4. Lubicate the lage eplacement O-ing and install it in the goove of the elay valve supply pot. xxxxx xxxxx xxxxx xxxxx RELAY VALVE SUPPLY PORT 5. Use two scews to attach the adapte to the elay valve. 6. Connect the ai supply line to the supply pot on the adapte. 7. Connect the foot valve contol line to the contol pot on the ATC valve. 8. Connect the haness connecto to the ATC valve. Hand tighten only. 9. Lowe the vehicle if it has been aised and emove the blocks. 10. Test the installation. 3-28

Component Removal and Installation Checking ATC Valve Installation 1. Stat the engine. 2. Fully chage the esevois with ai. 3. Shut off the engine. 4. Apply the bakes. 5. Listen fo ai leaks at the ATC valve. 6. Veify that the ABS and ATC indicato lamp opeates popely. 7. If the ABS and ATC indicato lamp does not go out, check fo faults. 8. Ease any faults found. 9. Recycle the ignition switch and check fo faults again. 3-29

Component Removal and Installation Pogess Check 3-3 Answe questions below befoe continuing to the next section. 1. The ATC foot valve contol line is connected to the pot on the ATC valve. 2. On an ABS valve package, the ATC ai supply line is connected to the to the supply pot on the. 3-30

Component Removal and Installation Notes 3-31

Meito WABCO Vehicle Contol Systems 2135 West Maple Road Toy, MI 48084-7121 USA 800-535-5560 meitowabco.com Infomation contained in this publication was in effect at the time the publication was appoved fo pinting and is subject to change without notice o liability. Meito WABCO eseves the ight to evise the infomation pesented o to discontinue the poduction of pats descibed at any time. Copyight 1999 TP-9738 AvinMeito, Inc. Revised 3-99 All Rights Reseved Pinted in USA 16579/22882