The Anti-lock Brake System (ABS) module receives wheel speed readings from each wheel speed sensor and processes this information to determine if an ABS event is necessary. The wheel speed sensor electrically senses each tooth of the wheel speed sensor indicators as it passes through the wheel speed sensor's magnetic field.
The ABS module continuously monitors and compares the rotational speed of each wheel, and when it detects an impending wheel lock, modulates hydraulic brake pressure to the appropriate brake caliper. This is accomplished by the ABS module triggering the Hydraulic Control Unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the ABS module returns the solenoid valves to their normal position, and normal (base) braking resumes.
The ABS module is self-monitoring. When the ignition switch is turned to the RUN position, the ABS module does a preliminary electrical check, and at approximately 8 mph (12 km/h) the pump motor is turned on for approximately one half-second. Any malfunction of the ABS causes the ABS to shut off and the yellow ABS warning indicator to illuminate, however, normal power assisted braking remains.
The traction control system controls wheelspin by modulating engine torque and applying, then releasing the appropriate rear brake to restore traction when driving on slippery or loose surfaces.
The traction control system can be disabled by pressing the traction control switch and is indicated by an indicator lamp in the traction control switch. The traction control will reset and return to normal traction assist when the ignition switch is cycled or when the traction control switch is pressed and released a second time.
Inspection And Verification
- Verify the malfunction.
- Verify the stoplamps operate correctly by applying and releasing the brake pedal with the ignition switch in the OFF position. If the stoplamps do not operate correctly repair as necessary. If the stoplamps operate correctly, proceed to the next step.
- Visually inspect for obvious signs of mechanical or electrical damage:
Electrical 2005 Models
Electrical 2000-04 Model Year
If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step. If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC) and select the vehicle to be tested from the scan tool menu. If the scan tool does not communicate with the vehicle:
- check that the program card is correctly installed.
- check the connections to the vehicle.
- check the ignition switch position.
- If the scan tool still does not communicate with the vehicle, refer to the scan tool operating manual.
Carry out the scan tool data link test. If the scan tool responds with:
- System passed, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out self-test diagnostics for the ABS module.
- If the DTCs retrieved are related to the concern, go to the Anti-Lock Brake System (ABS) Module Diagnostic Trouble Code (DTC) Index.
B1317: Battery Voltage High
B1318: Battery Voltage Low
B1342: ECU Is Defective
B1484: Brake Pedal Input Open Circuit
B1596: Repair Continuous Codes
B2477: Module Configuration Failure
C1095: ABS Hydraulic Pump Motor Circuit Failure
C1096: ABS Hydraulic Pump Motor Circuit Open
C1115: ABS Power Relay Output Short Circuit To Battery
C1145: RF Wheel Speed Sensor Input Circuit Failure
C1155: LF Wheel Speed Sensor Input Circuit Failure
C1165: RR Wheel Speed Sensor Input Circuit Failure
C1175: LR Wheel Speed Sensor Input Circuit Failure
C1185: ABS Power Relay Output Circuit Failure
C1194: ABS Outlet Valve Coil LF Circuit Failure
C1198: ABS Inlet Valve Coil LF Circuit Failure
C1210: ABS Outlet Valve Coil RF Circuit Failure
C1214: ABS Inlet Valve Coil RF Circuit Failure
C1222: Wheel Speed Mismatch
C1233: LF Wheel Speed Sensor Input Signal Missing
C1234: RF Wheel Speed Sensor Input Signal Missing
C1235: RR Wheel Speed Sensor Input Signal Missing
C1236: LR Wheel Speed Sensor Input Signal Missing
C1242: ABS Outlet Valve Coil LR Circuit Failure
C1246: ABS Outlet Valve Coil RR Circuit Failure
C1250: ABS Inlet Valve Coil LR Circuit Failure
C1254: ABS Inlet Valve Coil RR Circuit Failure
C1266: ABS Valve Power Relay Circuit Failure
C1329: ABS Valve Outlet Coil Over RF Temperature
C1330: ABS Valve Outlet Coil Over LR Temperature
C1331: ABS Valve Outlet Coil Over RR Temperature
C1332: ABS Valve Outlet Coil Over LF Temperature
C1333: ABS Valve Inlet Coil Over RF Temperature
C1334: ABS Valve Inlet Coil Over LR Temperature
C1335: ABS Valve Inlet Coil Over RR Temperature
C1336: ABS Valve Inlet Coil Over LF Temperature
C1404: Traction Control Valve Rear Circuit Failure
C1446: Brake Switch Circuit Failure
C1527: ABS TC Valve Inlet Coil Over Temperature
C1531: ABS TC Valve Outlet Coil Over Temperature
C1730: Reference Voltage Out of Range (+5 V)
C1805: Mismatched PCM and/or ABS module
C1958: ABS TC Valve Outlet Coil Failure
U0073: CAN Bus off - Transmit Error
U1009: SCP (J1850) Invalid or Missing Data for Engine Torque
U1027: SCP (J1850) Invalid or Missing Data for Engine RPM
U1059: SCP (J1850) Invalid or Missing Data for Transmission/Transaxle/PRNDL
U1083: SCP (J1850) Invalid or Missing Data for Engine Systems
U1262: SCP (J1850) Communication Bus Fault
U1900: CAN Communication Bus Fault - Receive Error