Inspection and Verification
- Verify the customer concern.
- Verify the stoplamps operate correctly by pressing and releasing the brake pedal with the ignition switch in the ON position. 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
- Wheel speed sensor rings
- ABS module
- Battery Junction Box (BJB) fuse(s):
- 9 (40A)
- 12 (20A)
- Power Steering Control Module (PSCM) (vehicles equipped with Electronic Power Assist Steering (EPAS))
- Restraints Control Module (RCM)
- Smart Junction Box (SJB) fuse(s):
- 34 (5A)
- 35 (10A)
- Stability/traction control switch
- Steering Angle Sensor Module (SASM) (vehicles equipped with Active Park Assist)
- Steering wheel rotation sensor (vehicles without EPAS)
- Stoplamp switch
- Wheel speed sensors
- Wiring, terminals or connectors
- 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.
- 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 continuous DTCs and 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 or the Instrument Cluster (IC) 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.