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.
- Visually inspect for obvious signs of mechanical or electrical damage.VISUAL INSPECTION CHART
Mechanical Electrical - Base brake system
- Hydraulic Control Unit (HCU)
- Incorrectly inflated tires
- Mismatched wheels or tires on vehicle
- Suspension components
- Wheel bearing magnetic strip
- ABS module
- Battery Junction Box (BJB) fuse(s):
- 1 (40A)
- 9 (20A)
- Central Junction Box (CJB) fuse(s):
- 22 (7.5A)
- Stoplamp switch
- PCM
- Wheel speed sensors
- Wiring, terminals or connectors
- 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.
- verify the scan tool operation with a known good vehicle.
- refer to MODULE COMMUNICATIONS NETWORK to diagnose no response from the PCM.
- 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 DTCs.
- Clear the continuous DTCs and carry out the self-test diagnostics for the ABS module.
- If the DTCs retrieved are related to the concern, go to the ABS Module DTC Chart or the IPC DTC Chart in DTC CHARTS . 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.