Backup Lamps Malfunction

Backup 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 BCK/UP fuse in the underhood fuse block supplies battery positive voltage to the normally open park/neutral position (PNP) switch of a vehicle equipped with an automatic transmission or the backup lamp switch if equipped with a manual transmission. When the driver places the gear selector lever is in the REVERSE position, the switch closes and the current flow is from the switch to the backup lamps.

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, with the transmission in park or neutral the backup lamps should not be on.
2. Shift the transmission into reverse, the backup lamps should be on.

Circuit/System Testing

1. Ignition OFF, disconnect the park neutral position or backup lamp switch connector.
2. Ignition ON, the backup lamps should not be illuminated.

• If the backup lamps are illuminated, test the listed backup lamp control circuit for a short to voltage.

* Park neutral position switch terminal 10
* Backup lamp switch terminal B

3. Connect a test lamp between the listed switch supply circuit and ground. The test lamp should illuminate.

* Park neutral position switch terminal 11
* Backup lamp switch terminal A

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

4. Connect a fused jumper wire between the listed switch supply circuit and backup lamp control circuit. Both backup lamps should illuminate.

* Park neutral position switch terminal 11 to terminal 10
* Backup lamp switch terminal A to terminal B

• If both backup lamps are not illuminated, test the backup lamp control circuit for a open/high resistance or short to ground.

• If one backup lamp is not illuminated test the affected control and ground circuits for an open/high resistance. If the circuits test normal replace the affected backup lamp bulb.

5. If all circuits test normal, test or replace the park neutral position or backup lamp switch.

Repair Instructions

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

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