GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

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 serial data messages to the IPC, in order to command the indicator ON or OFF.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Antilock Brake System Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List for EBCM

Circuit/System Testing

Important: Diagnose all vehicle DTCs before using this diagnostic. If a repair has been made, operate the vehicle so that the EBCM performs the self test. The ABS lamp will remain on until the self test completes after certain DTCs have been set, even if they have been cleared with a scan tool.

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