Domestic

Voltage is applied at all times to the PRK LAMP relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch ON signal circuit to the body control module (BCM) . The BCM then applies a ground to the park lamp relay control circuit. This energizes the relay and applies voltage through both PRK LAMP fuses and the park lamp supply voltage circuits illuminating the park, tail, and license lamps.

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Voltage is applied at all times to the PRK LAMP relay and the RT PRK LAMP relay from battery voltage. When the headlamp switch is placed in the PARK position, ground is applied through the park lamp switch signal circuit to the BCM. The BCM then applies a ground to both the park lamp relay control circuits. This energizes the relays and applies voltage through both PRK LAMP fuses and the park lamp supply voltage circuits illuminating the park, tail, and license lamps.

The ignition is ON. The park lamps must be commanded ON by the headlamp switch.

The BCM detects a short to voltage on the park lamp relay control circuit while trying to apply a ground to energize the relay.

The BCM turns off the park lamp relay control for the remainder of the ignition cycle.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

Ignition ON, turn the headlamp switch to the park lamps ON position. Observe the scan tool Park Lamp Relay Command parameter. The reading should display On and the park lamps should illuminate.

Caution: The high intensity discharge system produces high voltage and current. To reduce the risk of severe shocks and burns:

1. Ignition OFF, remove the appropriate PRK LAMP Relay from the rear fuse block.
2. Connect a test lamp between B+ and the appropriate control circuit terminal listed below.

•	PRK LAMP relay terminal 101

•	RT PRK LAMP relay terminal 92 - Export

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 the circuit tests normal, test or replace the park lamp relay.

Relay Test

1. Ignition OFF, disconnect the park lamp relay.
2. Test for 70-100 ohms of resistance between terminals 85 and 86.

⇒	If the resistance is not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

•

30 and 85

•

30 and 86

•

30 and 87

•

85 and 87

⇒	If not the specified value, replace the relay.

4. Install a 10A fused jumper wire between relay terminal 85 and B+. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms of resistance between terminals 30 and 87.

⇒	If greater than the specified range, replace the relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.