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
--- | --- | --- | --- | ---
Hazard Switch Signal | 2 | 1 | 1 | --
Hazard Switch Ground | -- | 1 | 1 | --
1. Hazard Lamps Inoperative 2. Hazard Lamps Always On

### Circuit/System Description

The body control module (BCM) controls the hazard lamps based on inputs from the hazard switch. With the hazard switch closed, a ground path is provided on the hazards switch signal circuit, indicating a hazard lamp request. When this request is seen, the BCM will pulse the turn signal lamp control circuits, illuminating the turn signal lamps.

### Reference Information

#### Schematic Reference

Exterior 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

1. Ignition ON, individually operate both the left and right turn signals. All appropriate lamps should flash when in each turn signal position.

⇒ | If any of the lamps do not flash, refer to Turn Signal Lamps and/or Indicators Malfunction.

2. Observe the scan tool Hazard Lamp Switch parameter while cycling the hazard switch. The parameter should change between Active and Inactive.

⇒ | If the parameter does not cycle between the specified values, refer to Hazard Switch Circuit Malfunction.

3. Press the hazard switch. All appropriate lamps should flash.

⇒ | If one or more lamps do not flash, replace the BCM.

### Circuit/System Testing

#### Hazard Switch Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the hazard switch.
2. Test for less than 5.0 ohms between the ground circuit terminal B and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Hazard Lamp Switch parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal C for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the signal circuit terminal C and the ground circuit terminal B. Verify the scan tool Hazard Lamp Switch parameter is Active.

⇒ | If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the hazard switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Hazard Warning Switch Replacement

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