Park, License, and/or Tail Lamps Malfunction

Park, License, and/or Tail 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, tail, marker, and license lamps are turned ON when the headlamp switch is placed in the PARK or ON position or anytime the headlights are requested. The underhood fuse block supplies battery voltage to both the park lamp relay switch contacts and the park lamp coil circuit. The body control module (BCM) provides a ground or control circuit to the park lamp relay coil circuit. When the park lamps are requested ON, the BCM energizes the park lamp relay. Current flow is from the park lamp relay to the individual park lamp circuit fuses and to their respective park, tail, marker, license and clearance lamps. The front park, marker, tail, and license lamps are grounded at G105. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, the park, tail, and license lamps will remain ON until turned OFF or the battery runs dead.

Reference Information
Schematic Reference

Exterior Lights Schematics (Exterior Lights Diagrams)
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, observe the scan tool BCM Parklamp Switch parameter while cycling the headlamp switch between the Park and Off positions. The parameter should cycle between Active and Inactive.

• If the parameter does not cycle between the specified values, refer to Headlamp Switch Circuit Test.

2. Command the Parking Lamps ON and OFF with a scan tool. Verify the park, license, and tail lamps turn ON and OFF.

• If any of the lamps do not cycle between the commanded states, refer to Exterior Lamps Circuit Test.

Circuit/System Testing

Headlamp Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal 3 and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, verify the scan tool BCM Parklamp Switch parameter is Off.

• If not the specified value, test the signal circuit terminal 2 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 2 and ground. Verify the scan tool BCM Parklamp Switch parameter is On.

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

5. If all circuits test normal, test or replace the headlamp switch.

Exterior Lamps Circuit Test
1. Ignition OFF, disconnect an affected park or license lamp bulb.
2. Verify that a test lamp illuminates when connected between battery voltage and the listed ground circuit terminal.

* Park or tail lamp terminal G
* License lamp terminal B

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

3. Ignition ON, connect a test lamp between the listed control circuit terminal and ground.

* Park or tail lamp terminal B
* License lamp terminal A

4. Turn the park lamp switch on and off and verify that the test lamp turns on an off.

• If the test lamp does not illuminate test the control circuit for an open/high resistance.
• If the test lamp remains illuminated test the control circuit for a short to voltage.

5. If all circuits test normal replace the affected bulb.

Repair Instructions

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

* Headlamp Switch Replacement (Service and Repair)
* Park/Turn Signal/Side Marker Lamp Bulb Replacement (Service and Repair)
* License Lamp Bulb Replacement (Service and Repair)
* Tail Lamp Bulb Replacement (Service and Repair)