Inspection and Verification
Anti-Lock Control
Inspection and Verification
Identifying the Brake System
Two ABS systems are available for this vehicle: ABS enhanced with EOTC and ABS enhanced with traction control and stability assist. ABS with traction control and stability assist may also be called Electronic Stability Control (ESC), Roll Stability Control (RSC(R)), AdvanceTrac(R) or IVD by the scan tool and other service publications.
ABS with traction control and stability assist can be identified by the presence of individual left and right rear wheel speed sensors.
ABS with EOTC can be identified by the absence of rear wheel speed sensors.
To diagnose ABS with traction control and stability assist, refer to Anti-Lock Control - Traction Control and Stability Assist.
1. Identify the brake system.
2. Verify the customer concern.
3. Verify the stop lamps operate correctly by pressing and releasing the brake pedal with the ignition switch in the OFF position. If the stoplamps do not operate correctly, refer to Exterior Lighting Testing and Inspection. If the stoplamps operate correctly, proceed to the next step.
4. Verify the base brake system operates correctly. If any concerns are present, address them before continuing with any ABS concerns. If the base brake system operates correctly, proceed to the next step.
5. Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart
6. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
7. 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).
8. NOTE: The Vehicle Communication Module (VCM) LED prove out confirms power and ground from the DLC are provided to the VCM.
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 Testing and Inspection, No Power To The Scan Tool, to diagnose no power to the scan tool.
9. If the scan tool does not communicate with the vehicle:
- verify the ignition key is in the ON position.
- verify the scan tool operation with a known good vehicle.
- refer to Module Communications Network Testing and Inspection to diagnose no response from the PCM.
10. Carry out the network test.
- If the scan tool responds with no communication for one or more modules, refer to Module Communications Network Testing and Inspection.
- If the network test passes, retrieve and record Continuous Memory Diagnostic Trouble Codes (CMDTCs).
11. Clear the CMDTCs and carry out the self-test diagnostics for the ABS module and the IPC.
12. If the DTCs retrieved are related to the concern, GO to the ABS Module DTC Chart Anti-Lock Control or the Instrument Panel Cluster (IPC) DTC Chart. For all other DTCs, refer to Multifunction Electronic Modules Testing and Inspection.
13. If no DTCs related to the concern are retrieved, GO to Symptom Chart. Anti-Lock Control
Drive Cycle Test
The drive cycle test can be used as a system evaluation test, a repair verification test or during diagnosis (for intermittent concerns).
For system evaluation, the customer may only have a general concern about the way the vehicle is braking. There may not be a clear system concern to troubleshoot. This test is designed to produce common system concern symptoms. Once a symptom is found, a symptom diagnostic procedure can be followed to repair the vehicle.
Always use this test after vehicle repairs because the ABS module is unable to detect some system concerns unless the vehicle is driven under specific conditions. After completing the drive cycle test, carry out the self-test using the scan tool.
NOTE: Wetting down the area where the testing is to be carried out aids in this test.
NOTE: An assistant should be used to monitor the wheels during the ABS stop. Momentary lockup is permissible.
1. While driving the vehicle approximately 16 km/h (10 mph), press the brake pedal hard enough to lock all 4 wheels.
2. Does one wheel lock consistently?
- If yes and the yellow ABS warning indicator is not illuminated, GO to Symptom Chart. Anti-Lock Control
- If yes and the yellow ABS warning indicator is illuminated, retrieve and document the DTCs. Proceed to the ABS Module DTC Chart. Anti-Lock Control
3. While driving the vehicle approximately 32 km/h (20 mph), perform a light-to-medium (normal traffic) stop.
4. Does the pump motor turn on and are brake pedal pulsations felt at any time during the stop?
- If yes and the yellow ABS warning indicator is not illuminated, GO to Symptom Chart. Anti-Lock Control
- If yes and the yellow ABS indicator is illuminated, retrieve and document ABS module DTCs. Proceed to the ABS Module DTC Chart. Anti-Lock Control
5. Clear all CMDTCs.
6. Start the vehicle and shift the transmission into low gear.
7. Allow the vehicle to creep forward at idle for at least 45 seconds.
8. Does the yellow ABS indicator illuminate?
- If yes, retrieve and document the DTCs. Proceed to the ABS Module DTC Chart. Anti-Lock Control
9. Slowly accelerate to 40 km/h (25 mph). Let at least 45 seconds elapse before reaching 40 km/h (25 mph).
10. Does the yellow ABS warning indicator illuminate?
- If yes, retrieve and document the DTCs. Proceed to the ABS Module DTC Chart. Anti-Lock Control
11. Has the customer concern been addressed and corrected by the previous actions?
- If yes, the system is OK.
- If no, GO to Symptom Chart. Anti-Lock Control