Identifying the Brake System
- Verify the customer concern.
- 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, refer to EXTERIOR LIGHTING . If the stoplamps operate correctly, proceed to the next step.
- Verify the PRNDL operates correctly on the instrument cluster. If the PRNDL does not operate correctly, refer to INSTRUMENTATION, MESSAGE CENTER, AND WARNING CHIMES . If the PRNDL 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
- Incorrectly inflated tires
- Mismatched wheels or tires on vehicle
- Stability control sensor cluster installation
- Steering Angle Sensor Module (SASM) installation
- Steering components and suspension components
- Wheel speed sensor magnetic strips
- ABS module
- Battery Junction Box (BJB) fuse(s):
- 12 (30A)
- 15 (20A)
- Central Junction Box (CJB) fuse 161 (7.5A)
- Hydraulic Control Unit (HCU)
- SASM
- Stability control sensor cluster
- Stoplamp switch
- 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 Diagnostic Trouble Codes (CMDTCs).
- Carry out the self-test diagnostics for the ABS module.
- If the DTCs retrieved are related to the concern, go to ABS Module 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.
NOTE:
The vehicle must be at a complete standstill and on a level surface while carrying out the self-test. Any movement of the vehicle during the self-test may result in false DTCs being set.