Backup Lamps Malfunction

Backup Lamps Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

Battery voltage is applied from the HTD/SEAT/BCK/UP fuse located in the underhood fuse block to the park/neutral position (PNP) switch when the ignition switch is in the RUN or CRANK positions. When the transmission is placed in the REVERSE position, the park/neutral position (PNP) switch contacts close providing battery voltage to the backup lamps. With both power and ground the backup lamps illuminate. Once the driver moves the gear selector out of the REVERSE position, the park/neutral position (PNP) switch contacts open and the backup lamps turn OFF.

Reference Information
Schematic Reference

Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior Lighting Systems)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Verification

Ignition ON, engine running, turn the backup lamps ON and OFF by going between the park and reverse gears. The backup lamps should turn ON and OFF when changing between the selected states.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate backup lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohm between the ground circuit terminal B and ground.

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

3. Connect the harness connector at the backup lamp.
4. Ignition OFF, disconnect the harness connector at the park/neutral position (PNP) switch.
5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

6. Verify that a test lamp does not illuminate between the control circuit terminal 4 and ground.

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

7. Connect a 10 A fused jumper between the B+ circuit terminal 5 and the control circuit terminal 4. Ignition ON, verify the backup lamps are illuminated.

• If the backup lamps do not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the backup lamp.

8. If all circuits test normal, replace the park/neutral position (PNP) switch.

Repair Instructions

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

* Park/Neutral Position Switch Replacement (Service and Repair)
* Backup Lamp Replacement (Service and Repair)