Inspection and Verification

Anti-Lock Control

Inspection and Verification

NOTE: Refer to the Description and Operation Intelligent Access (IA) with Push Button Start in Antitheft and Alarm Systems to review the procedures for achieving the various ignition states (ignition in accessory, ignition on, ignition start, ignition off) on vehicles with this feature.

1. Verify the customer concern.

2. 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 Lighting and Horns. If the stoplamps operate correctly, proceed to the next step.

3. Visually inspect for obvious signs of mechanical or electrical damage.

Visual Inspection Chart






4. NOTE: Make sure to use the latest scan tool software release.

If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).


5. NOTE: The Vehicle Communication Module (VCM) LED prove out confirms power and ground from the DLC (Data Link Connector) are provided to the VCM (Vehicle Communication Module).

If the scan tool does not communicate with the VCM (Vehicle Communication Module):

- check the VCM (Vehicle Communication Module) connection to the vehicle.

- check the scan tool connection to the VCM (Vehicle Communication Module).

- refer to - No Power To The Scan Tool, to diagnose no power to the scan tool.


6. If the scan tool does not communicate with the vehicle:
- verify the ignition is ON.
- The air bag warning indicator prove-out (other indicators may NOT prove ignition is ON) confirms ignition ON. If ignition does not turn ON, refer to Steering Column to diagnose no power in RUN.

- verify the scan tool operation with a known good vehicle.

- refer to Information Bus Inspection and Verification to establish a scan tool session (without the ignition ON). Inspection and Verification


7. Carry out the network test.
- If the scan tool responds with no communication for one or more modules, refer to Information Bus.

- If the network test passes, retrieve and record Continuous Memory Diagnostic Trouble Codes (CMDTCs).


8. Clear the CMDTCs (Continuous Memory Diagnostic Trouble Codes) and carry out the self-test diagnostics for the ABS module.

9. 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 Body Control Systems. Antilock Brakes / Traction Control Systems

10. If no DTCs related to the concern are retrieved, GO to Symptom Chart. Symptom Related Diagnostic Procedures