For 1990-2009 cars

### Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle. Refer to Diagnostic System Check - Vehicle , prior to using this diagnostic procedure.

### Circuit/System Description

The instrument cluster controls the operation of the ABS indicator. The electronic brake control module (EBCM) reports the desired status of the ABS indicator via serial data messages. The ABS indicator signal circuit is a back-up reporting circuit to the serial data messages. The EBCM supplies ground through the circuit when the ABS is operating correctly. When there is a concern with ABS that should turn on the ABS indicator, the EBCM opens the ABS indicator signal circuit. If there is a concern with the ABS serial data messages, the instrument cluster uses the ABS indicator signal to determine if the ABS indicator should be illuminated. Using the serial data messages and back-up circuit, the instrument cluster decides whether to turn the ABS indicator on.

### Reference Information

#### Schematic Reference

Antilock Brake System Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Testing

1. Verify the electronic brake control module (EBCM) ground is clean and torqued to the correct specification.

⇒ | If the EBCM ground is not clean and not torqued to the correct specification clean and retension the EBCM ground terminal.

2. Install a scan tool.
3. Ignition ON, engine OFF, observe the ABS Failed parameter in the Body/EBCM/data list.

⇒ | If the indicator parameter does not display OFF inspect for poor connections at the harness connector of the EBCM.

⇒ | If the connections at the harness connector of the EBCM are OK, replace the EBCM.

4. Ignition ON, engine OFF, observe the ABS indicator on the instrument panel cluster (IPC) during the displays test.

⇒ | If the ABS indicator does not illuminate during the displays test and then turn OFF inspect for poor connections at the harness connector of the IPC.

⇒ | If the connections at the harness connector of the IPC are OK, replace the IPC.

### Repair Instructions

• | Electronic Brake Control Module Replacement .

• | Instrument Cluster Replacement .

• | Electronic Brake Control Module Programming and Setup .

• | Instrument Cluster Programming and Setup .