Hazard Lamps Malfunction

Hazard Lamps Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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/System Description

The hazard flashers may be activated in any power mode. The hazard switch is permanently grounded through G200. When the hazard switch is placed in the ON position, ground is applied through the hazard switch signal circuit to the body control module (BCM). The BCM supplies battery voltage to all four turn signal lamps in an ON and OFF duty cycle. When the hazard switch is activated, the BCM sends a GMLAN serial data message to the instrument panel cluster (IPC) requesting both turn signal indicators to be cycled ON and OFF. For more detailed information concerning hazard lamp operation refer to Exterior Lighting Systems Description and Operation.

Circuit/System Testing

Hazard Lamps Malfunction
1. Ignition OFF, disconnect the harness connector at the hazard switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal A.

• If the test lamp does not illuminate, 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 D 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 D and ground. Verify the scan tool hazard lamp switch parameter is ACTIVE.

• If not the specified value, test the signal circuit terminal D for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

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

Hazard Lamp Indicators Malfunction

Ignition ON, with a scan tool perform the display test for the instrument panel cluster (IPC) and observe both turn signal indicators.

If both turn signal indicators illuminate during the test, replace the BCM.

If both turn signal indicators do not illuminate during the test or remain illuminated at all times, replace the IPC.

Repair Instructions

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

* Hazard Warning Switch Replacement (Left Hand Drive) Hazard Warning Switch Replacement (Right Hand Drive)
* Control Module References for BCM or IPC replacement, setup, and programming. Programming and Relearning