Anti-Lock Braking Systems (ABS) for Trucks ... - Meritor WABCO

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Section 3TroubleshootingIgnition VoltageVoltage must be between 11.0 and 15.0 v. Measurevoltage between pin 9 and pin 27 on cab mountsystems and between 10 and 12 on the 19-pinconnector on frame-mounted ECUs with ignition on.Sensor ResistanceThe sensor circuit resistance must be700-3000 ohms. Resistance can be measured atthe sensor connector when it is removed fromthe ECU, or right at the sensor when the extensioncable is removed.Sensor AdjustmentNOTEOn the steering axle the sensor is accessible on thein-board side of the steering knuckle.On the drive axle the wheel and drum assemblymust be pulled to gain access to the sensor.Gently push the sensor in toward the tooth wheeluntil it contacts the tooth wheel. When the resistance is greater than 8.0 ohms,clean the electrical contacts in the solenoid. Check the resistance again. To check the cable and the ABS valve as one unit,measure across the pins on the ECU connectorof the cab harness. Reference the diagram of thesystem you are testing for pin numbers (seeSection 5, "Wiring").ATC ValveThe resistance across the two electrical terminalson the ATC valve must be 8.0 to 14.0 ohms.Figure 3.23.Figure 3.23ABS Valve The resistance across each valve solenoid coilterminal and the ground on the ABS valveconnector must be 4.0 to 8.0 ohms. Figure 3.22.Figure 3.221 Ground Terminal2 Exhaust Solenoid3 Inlet Solenoid If the resistance is greater than 14.0 ohms, cleanthe electrical contacts on the solenoid. Check the resistance again. To check the cable and ATC valve as one unit,measure the resistance across the pins:— Use the connector at the connection point ofthe ECU for frame mounts— Use the Meritor WABCO test adaptor forcab mounts Reference the diagram of the system you aretesting for pin numbers (see Section 5, "Wiring").Page 25
Section 3TroubleshootingDynamometer Testing Vehicleswith ATCWARNINGFailure to disable the ATC before dynamometertesting could result in serious personal injury anddamage to the vehicle.Vehicles with the ATC option must have the ABSsystem power disabled to test the vehicle on adynamometer. The method requires removing the“ABS” circuit breaker/fuse or removing the ECUmain connector. Disconnect connector or breakerwith ignition in the OFF position.Tire Size RangeCAUTIONFor proper ABS/ATC operation with the standardElectronic Control Unit (ECU), front and reartire sizes must be within ± 5% of each other.When this tire size range is exceeded withoutelectronically modifying the ECU, the systemperformance can be affected and the warning lampcan illuminate. Call Meritor WABCO at800/535-5560 when you plan a tire size differencegreater than 5%.Calculate tire size with the following equation:% Difference = (RPM Steer ÷ RPM Drive — 1) x 100RPM = tire revolutions per milePage 26
Page 1 and 2: Anti-Lock Braking Systems(ABS) for
Page 3 and 4: Table of ContentsAsbestos and Non-A
Page 5 and 6: NotesPage 2
Page 7 and 8: Section 1IntroductionABS Components
Page 9 and 10: Section 1IntroductionFigure 1.9Opti
Page 11 and 12: NotesPage 8
Page 13 and 14: Section 3TroubleshootingErasing a f
Page 15 and 16: Section 3TroubleshootingBlink Code
Page 17 and 18: Section 3TroubleshootingAdditional
Page 19 and 20: Section 3TroubleshootingAdditional
Page 21 and 22: Section 3TroubleshootingFigure 3.7F
Page 23 and 24: Section 3TroubleshootingTable 1 —
Page 25 and 26: Section 3TroubleshootingFinal Test
Page 27: Section 3TroubleshootingSensorsFigu
Page 31 and 32: Section 4Removal & Installation2. R
Page 33 and 34: Section 5WiringSection 5WiringThis
Page 35 and 36: Section 5WiringABS/ATC Wiring Schem
Page 37 and 38: Section 5WiringABS/ATC Wiring Schem
Page 39 and 40: Section 5WiringFront/Rear Configura
Page 41 and 42: Section 5WiringIn-Cab ECU Wiring Di
Page 43: Meritor WABCOVehicle Control System

Anti-Lock Braking Systems (ABS) for Trucks ... - Meritor WABCO

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