The hazard flashers may be activated in any power mode. The hazard switch is located on the accessory control panel and is permanently grounded through ground G205. When the hazard switch is placed in the ON position, ground is applied through the hazard switch signal circuit to the instrument panel cluster (IPC). The IPC responds by sending a serial data message to the underhood electrical center (UEC) and the rear electrical center (REC) requesting the front and rear turn signal lamps be illuminated in an ON and OFF duty cycle. The UEC and REC respond by applying voltage to there respective turn signal control circuits illuminating the front and rear turn signal lamps ON and OFF. The IPC is also responsible for cycling both turn signal indicators ON and OFF. The IPC illuminates the hazard switch telltale by applying voltage to the hazard switch telltale signal circuit.

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

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Hazard Warning Switch parameter while cycling the hazard switch ON and OFF. The parameter should change between Off and On.

⇒	If the parameter does not change between the commanded states, refer to Hazard Lamps Malfunction.

2. Ignition ON, with a scan tool command the Hazard Warning LED Test ON and OFF. The hazard switch telltale indicator should turn ON and OFF when commanded.

⇒	If the hazard switch telltale indicator does not illuminate when commanded, refer to Hazard Switch Telltale Malfunction.

3. Activate the hazard switch and observe the turn signal indicators on the IPC. Both turn signal indicators should cycle ON and OFF repeatedly.

⇒	If the turn signal indicators do not cycle ON and OFF, refer to Hazard Lamp Indicators Malfunction.

Hazard Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the hazard switch.
2. Ignition OFF, verify 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 Warning Switch parameter is Off.

⇒	If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the IPC.

4. Install a 3A fused jumper wire between the signal circuit terminal 6 and ground. Verify the scan tool Hazard Warning Switch parameter is On.

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

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

Hazard Switch Telltale Malfunction

1. Ignition OFF, disconnect the harness connector at the hazard switch.
2. Ignition OFF, verify 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. Connect a test lamp between the control circuit terminal 15 and ground.
4. Command the Hazard Warning LED Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the IPC.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the IPC.

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

Hazard Lamp Indicators Malfunction

Ignition ON, with a scan tool perform the Turn Signal Telltale Test for the instrument panel cluster (IPC) and observe the left and right turn signal indicators.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.