Park Lamps Malfunction

Park 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.

Circuit/System Description

The PARK/LAMP fuse in the instrument panel (I/P) fuse block supplies battery positive voltage to both the coil and switch sides of the PRK LAMP relay, also located in the I/P fuse block. When the headlamp switch is placed in either the PARK or HEAD position, ground is supplied to the BCM on the park lamp switch ON signal circuit. The BCM then applies a ground to the park lamp relay control circuit. This energizes the relay, applying voltage to all park, tail, marker, and license lamps. The park, tail, marker, and license lamps are also turned ON when the headlamps are commanded ON by the BCM for low light operation. Ground for the headlamp switch is from G200. Grounds for the various lamps are as follows:

* G100 supplies the right front lamps
* G101 supplies the left front lamps
* G400 supplies the right rear lamps
* G401 supplies the left rear lamps

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) for Scan Tool Information

Circuit/System Verification

1. Ignition ON, command the park lamps ON and OFF with a scan tool. The park lamps should illuminate when commanded ON.

• If the park lamps do not illuminate, Refer to Park Lamps Inoperative From BCM.

• If the park lamps are always illuminated, Refer to Park Lamps Always On From Relay.

2. Refer to Park Lamps Inoperative From Switch.

Circuit/System Testing

Park Lamps Inoperative From BCM
1. Ignition OFF, disconnect the PRK LAMP relay.
2. Ignition ON, verify that a test lamp illuminates between the relay switch B+ circuit and ground.

• If the test lamp does not illuminate, replace the rear fuse block.

3. Test the relay controlled output circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the PRK LAMPS relay.

Park Lamps Always On From Relay
1. Ignition OFF, disconnect the PRK LAMP relay.
2. Ignition ON, verify that the park lamps are not illuminated.

• If the park lamps are illuminated, test the relay controlled output circuit for a short to voltage.

3. If all circuits test normal, replace the PRK LAMP relay.

Park Lamps Inoperative From Switch
1. Disconnect the harness connector at the headlamp switch.
2. Install a 3A fused jumper wire between the park lamp switch signal circuit terminal 6 and ground. Verify the scan tool Park Lamp Switch parameter is On.

• If not the specified value, test the signal circuit terminal 6 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

3. Test the signal circuit terminal 6 for a short to ground. If all circuits test normal, replace the headlamp switch.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Headlamp Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning)