Battery voltage is applied at all times from the PARK LAMPS fuse to both the coil and switched sides of the PARK LAMP relay in the underhood electrical center. Ground is applied from G201 to the multifunction switch at all times. When the headlamp switch is place in either the HEAD or PARK position, ground is applied to the park lamp relay control circuit. This energizes the PARK LAMP Relay and applies battery positive voltage to all of the park, tail, license, and marker lamps.

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

Ignition ON, observe the scan tool Park Lamp Switch parameter while cycling the park lamp switch between the ON and OFF positions. The readings should toggle between On and Off.

Park Lamp Switch Malfunction

1. Ignition OFF, disconnect the X3 harness connector at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal K.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Park Lamp Switch parameter is Off.

⇒	If not the specified value, test the signal circuit terminal M 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 M and ground. Verify the scan tool Park Lamp 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 BCM.

5. If all circuits test normal, test or replace the turn signal/multifunction switch.

Park, License, and/or Tail Lamps Malfunction

1. Ignition OFF, disconnect the park lamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal C9 and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the B+ circuit terminal A9 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal C9 for a short to ground. If the circuit tests normal, test or replace the park lamp relay.

4. Verify that a test lamp illuminates between the B+ circuit terminal A8 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

5. Disconnect the harness connector at the inoperative park lamp.
6. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit and ground.

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

7. Connect the harness connector at the inoperative park lamp.
8. Connect a 10A fused jumper wire between the B+ circuit terminal A8 and the control circuit terminal C9. Verify the park lamps are activated.

⇒	If the park lamps do not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the inoperative park lamp.

9. Connect a test lamp between the B+ circuit terminal A9 and the control circuit terminal C8.
10. Command the parks lamps ON and OFF with the park lamp switch. The test lamp should turn ON and OFF when changing between the commanded states.

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

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

11. If all circuits test normal, test or replace the park lamp relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.