For 1990-2009 cars

### 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 cruise control engaged indicator based on serial data messages received from the engine control module (BCM) or the powertrain control module (ECM). The indicator is commanded ON when the cruise control system is controlling vehicle speed, and turned OFF with the system disengaged.

### Diagnostic Aids

This diagnostic assumes the cruise control system is functioning normally and there are no DTCs set. If the cruise control system is malfunctioning, refer to Cruise Control Malfunction.

### Reference Information

#### Schematic Reference

• | Cruise Control Schematics

• | Instrument Cluster Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

• | Cruise Control Description and Operation

• | Indicator/Warning Message Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, perform the scan tool Lamp Test. Verify the cruise control indicator illuminates.

⇒ | If the indicator does not illuminate, replace the K9 BCM.

2. Replace the K20 ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM, or BCM replacement, setup, and programming