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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Front Fog Lamp Indicator Control | 1 | 1 | 2 | --
1. Front fog lamp indicator inoperative. 2. Front fog lamp indicator always on.

### Circuit/System Description

With both the ignition switch in the RUN position and the park lamps or low beam head lamps ON, the fog lights will illuminate when the driver presses the fog lamp switch. When the fog lamps are on the BCM will turn the fog lamp indicator on by supplying battery voltage to the indicator LED through the indicator control circuit. The indicator is grounded through the headlamp switch low reference circuit to the BCM.

### Reference Information

#### Schematic Reference

Fog Lights Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exterior Lighting Systems 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

Ignition ON, command the front fog lamps ON and OFF with a scan tool. The front fog lamp indicator should turn on and off.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition ON, headlamps ON, connect a test lamp between the indicator control circuit terminal 8 and ground. The test lamp should not be illuminated.

⇒ | If the test lamp is illuminated, test the indicator control circuit for a short to voltage. If the circuit tests normal replace the BCM.

3. Command the front fog lamps ON with a scan tool. The test lamp should be illuminated.

⇒ | If the test lamp is not illuminated, test the indicator control circuit for an open/high resistance or short to ground. If the circuit tests normal replace the BCM.

4. If all the circuits test normal replace the headlamp switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Headlamp Switch Replacement

• | Control Module References for BCM replacement, programming, and setup