ABS Indicator Malfunction

ABS Indicator Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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 high speed GMLAN serial data message to the body control module (BCM), to request the indicator to turn ON or OFF. The BCM sends the request to the IPC on the class 2 serial data bus.

Reference Information
Schematic Reference

* Antilock Brake System Schematics (Electrical Diagrams)
* Data Communication Schematics (Electrical Diagrams)
* Instrument Cluster Schematics (Instrument Cluster Schematics)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

* ABS Description and Operation (Description and Operation)
* Indicator/Warning Message Description and Operation (Indicator/Warning Message)

Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for Scan Tool Information

Circuit Verification

Ignition ON. Observe the ABS indicator turn ON then OFF during the IPC bulb test.

Circuit/System Testing

1. Ignition ON. With a scan tool command the IPC display test ON and OFF. The ABS indicator should turn ON and OFF.

• If the ABS indicator does not turn ON and OFF when commanded, replace the IPC.

2. Replace the EBCM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for EBCM or IPC replacement, setup, and programming