Diagnostic Instructions
Circuit/System 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 a class 2 message to the IPC, in order to command the indicator
ON or OFF.
Diagnostic Aids
| • | If your vehicle is showing the brake or low air warning light is on and you either are not equipped with ABS or do not have an ABS warning light ON then there is a problem with the regular brake system. |
| • | Replace the Instrument Panel Cluster (IPC) if the ABS indicator intermittently fails to operate during the bulb check. |
| • | The malfunction must be present during diagnosis in order to prevent unnecessary parts replacement. Always begin diagnosis with the Diagnostic System Check. |
| • | After a wheel speed sensor DTC is cleared and the ignition is ON, the ABS indicator may remain ON until the 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. |
Reference Information
Schematic Reference
Antilock Brake System Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
ABS Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for EBCM and IPC
Circuit/System Verification
With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel warning lamps ON and OFF. The ABS Warning light should turn on and off with each command.
Circuit/System Testing
Important: Diagnose all vehicle DTCs before using this diagnostic.
With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel warning lamps OFF.
| ⇒ | If the ABS warning lamp does not turn OFF, replace the IPC. |
| ⇒ | If the ABS lamp turns OFF and there are no DTCs stored in any vehicle systems, replace the EBCM. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for EBCM or IPC replacement, setup, and programming
Repair Verification
- Turn OFF the ignition for 5 seconds.
- Turn ON the ignition, while observing the ABS Warning Light Indicator.
- The ABS Warning Light Indicator should light for 2 seconds then turn off.
| ⇒ | If the ABS indicator does not light, recheck the circuit/system testing. |
