Hazard Lamps Malfunction
Hazard Lamps Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The hazard flashers may be activated in any power mode. The instrument panel module (IPM) monitors the signal circuit of the hazard switch. When the hazard switch is placed in the ON position, the switch contacts close and battery positive voltage from the IPM flows through the hazard switch to G201. The rear integration module (RIM) turn lamp supply voltage circuit is also provided with ground through the hazard switch when the contacts close at G201 which in turn illuminates the hazard switch LED. The IPM relays the hazard switch status to the rear integration module (RIM) via the GMLAN serial data circuit. The RIM uses the status of the hazard switch to command the turn signals ON and OFF. The RIM controls both front and rear turn signals. The IPM sends a message via GMLAN to the instrument panel cluster (IPC) to enable both turn signal indicators in an ON and OFF duty cycle when the hazard switch is placed in the ON position. Voltage is supplied to the front and rear turn signals by the RIM. Ground is provided to the front turn signals at G104. The rear turn signals are grounded at G401 and G402.
Reference Information
Schematic Reference
Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)
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 2.
• 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 1 for a short to ground. If the circuit tests normal, replace the IPM.
4. Install a 3A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool hazard lamp switch parameter is ACTIVE.
• If not the specified value, test the signal circuit terminal 1 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPM.
5. If all circuits test normal, test or replace the hazard switch.
Hazard Lamp Indicator 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 2.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, left turn signal ON, verify that a test lamp illuminates between the voltage supply circuit terminal 4 and ground.
• If the test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the RIM.
• If the test lamp is always ON, test the voltage supply circuit for a short to voltage. If the circuit tests normal, replace the RIM.
4. If all circuits test normal, test or replace the hazard switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Hazard Warning Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for IPM or RIM replacement, setup, and programming