Battery positive voltage is applied at all times to both the coil and switched sides of the PRK LAMP relay. The park lamps are controlled by the body control module (BCM) by inputs from park lamp switch. When the BCM receives a park lamps ON command, it grounds the park lamps relay control circuit in order to energize the PRK LAMP relay. With the relay energized, battery voltage is applied through switch side of the relay, both PARK fuses, and the park lamp supply voltage circuits to all park, tail, and marker lamps.

Park lamps ON.

The BCM detects a short to voltage on the park lamp relay control circuit.

The BCM will deactivate the PRK LAMP relay for the remainder of the ignition cycle.

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, turn the park lamps on. The park lamps should illuminate.

1. Ignition OFF, disconnect the park lamp relay.
2. Connect a test lamp between the control circuit terminal 86 and B+.
3. Ignition ON, command the Parking Lamps 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 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.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.