Circuit Description
The instrument panel cluster (IPC) illuminates the antilock brake system (ABS) indicator by supplying ground to the lamp. The electronic brake control module (EBCM) sends class 2 serial data messages to the IPC in order to command the indicator ON or OFF.
Diagnostic Aids
Important: Do not proceed with this document if any DTCs are present, or if the ABS module is not communicating with the scan tool. Follow the diagnostic procedures for the listed DTCs, or for Data Communications. Intermittent symptoms indicate possible problems with wiring, connectors, or grounds. Make sure the EBCM has clean and tight ground contacts. Check for corrosion of crimped terminal connections in EBCM connector. The malfunction must be present during diagnosis in order to prevent unnecessary parts replacement. Always begin diagnosis with the Diagnostic System Check.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
|
Important: After a wheel speed sensor DTC is cleared and the ignition is ON, the antilock brake system (ABS) indicator may remain ON until the electronic brake control module (EBCM) completes a power-up self test. This test concludes when the vehicle reaches a speed greater than 20 km/h (13 mph) and the wheel speeds are verified by the EBCM. | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the ABS indicator illuminate for 2 seconds and then turn OFF? | Go to Diagnostic Aids | Go to Step 3 |
Does the ABS indicator turn OFF? | Go to Step 5 | Go to Step 4 | |
4 | Replace the IPC. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
5 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
6 |
Does the ABS indicator illuminate for 2 seconds and then turn OFF? | System OK | Go to Step 3 |
