Inspection and Verification
- Verify the customer concern.
- Verify the stoplamps operate correctly by pressing and releasing the brake pedal. If the stoplamps do not operate correctly, refer to EXTERIOR LIGHTING . If the stoplamps operate correctly, proceed to the next step.
- Verify the base brake system operates correctly. If any concerns are present, address them before continuing with any ABS concerns. Refer to BRAKE SYSTEM - GENERAL INFORMATION . If the base brake system operates correctly, proceed to the next step.
- Visually inspect for obvious signs of mechanical or electrical damage.VISUAL INSPECTION CHART
Mechanical Electrical - Base brake system
- Hydraulic Control Unit (HCU)
- Steering components, suspension components and tire size
- Tire pressure
- Mismatched tires
- Wheel and tire sizes
- ABS module
- Battery Junction Box (BJB) fuse(s):
- 5 (40A)
- 43 (30A)
- 92 (10A)
- Brake fluid level switch
- Stoplamp switch
- Wiring, terminals or connectors
- Wheel speed sensor
- 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).
- If the scan tool does not communicate with the VCM:
- Check the VCM connection to the vehicle.
- Check the scan tool connection to the VCM.
- Refer to MODULE COMMUNICATIONS NETWORK , No Power To The Scan Tool, to diagnose no power to the scan tool.
- If the scan tool does not communicate with the vehicle:
- Verify the ignition is ON.
- The air bag indicator (other indicators may not prove ignition ON. If the ignition does not turn on, refer to STEERING COLUMN SWITCHES to diagnose no power in RUN.
- Verify the scan tool operation with a known good vehicle.
- Refer to MODULE COMMUNICATIONS NETWORK to diagnose no response from the PCM.
- Verify the ignition is ON.
- Carry out the network test.
- If the scan tool responds with no communication for one or more modules, refer to MODULE COMMUNICATIONS NETWORK .
- If the network test passes, retrieve and record Continuous Memory Diagnostic Trouble Codes (CMDTCs).
- Clear the CMDTCs and carry out the self-test diagnostics for the ABS module, the SCCM and the IPC.
- If the DTCs retrieved are related to the concern, go to the ABS Module DTC Chart , or the IPC DTC Chart . For all other DTCs, refer to MULTIFUNCTION ELECTRONIC MODULES .
- If no DTCs related to the concern are retrieved, GO to Symptom Chart .
NOTE:
Make sure to use the latest scan tool software release.
NOTE:
The Vehicle Communication Module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM.