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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.

Diagnostic Fault Information





Circuit/System Description

Manual Transmission

Battery voltage is applied to the backup lamp switch when the ignition switch is in the RUN or CRANK positions. When the transmission is placed in the REVERSE position, the backup lamp switch provides battery voltage to the backup lamps. The backup lamps are permanently grounded at G105. With both power and ground the backup lamps illuminate. Once the driver moves the gear selector out of the REVERSE position, the backup lamp switch contacts open and the backup lamps turn OFF.

Automatic Transmission

Battery voltage is applied 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 PNP switch provides battery voltage to the backup lamps. The backup lamps are permanently grounded at G105. With both power and ground the backup lamps illuminate. Once the driver moves the gear selector out of the REVERSE position, the 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 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 Testing

Backup Lamps Malfunction - Automatic Transmission
1. Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal G and ground.

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

3. Connect the harness connector at the inoperative backup lamp.
4. Ignition OFF, disconnect the harness connector at the backup lamp switch.
5. Ignition ON, verify that a test lamp illuminates between the control circuit terminal A and ground.

• If the test lamp does not illuminate, test the control 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 B and ground.

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

7. Connect a 15-amp fused jumper between the control circuit terminal A and the control circuit terminal B. Verify the backup lamps illuminate.

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

8. If all circuits test normal, test or replace the backup lamp switch.

Backup Lamps Malfunction - Manual Transmission
1. Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal G and ground.

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

3. Connect the harness connector at the inoperative backup lamp.
4. Ignition OFF, disconnect the harness connector at the PNP switch.
5. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 11 and ground.

• If the test lamp does not illuminate, test the control 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 10 and ground.

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

7. Connect a 15-amp fused jumper between the control circuit terminal 11 and the control circuit terminal 10. Verify the backup lamps illuminate.

• If the backup lamps do not illuminate, test the control circuit terminal 10 for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the inoperative backup lamp.

8. If all circuits test normal, test or replace the PNP switch.

Repair Instructions

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

* Tail Lamp Replacement (Service and Repair)
* Backup Lamp Bulb Replacement (Service and Repair)
* Manual Shift Detent Lever with Shaft Position Switch Assembly Replacement (Service and Repair)

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