Backup Lamps Malfunction (Manual Transmission)

Backup Lamps Malfunction (Manual Transmission)

Diagnostic Instructions

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

Diagnostic Fault Information





Circuit/System Description

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 G402. 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.

Circuit/System Testing

1. Disconnect the harness connector at the inoperative backup lamp.
2. Test for less than 1.0 ohm of resistance between the inoperative backup lamp 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 backup lamp switch.
5. Ignition ON, verify that a test lamp illuminates between the backup lamp switch voltage supply circuit terminal A and ground.

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

6. Verify that a test lamp does not illuminate between the backup lamp voltage supply circuit terminal B and ground.

• If the test lamp illuminates, repair the backup lamp voltage supply circuit for a short to voltage.

7. Connect a 10-amp fused jumper between the backup lamp switch voltage supply circuit terminal A and the backup lamp voltage supply circuit terminal B. Verify the backup lamps are activated.

• If the backup lamps do not activate, repair the voltage supply 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.

Repair Instructions

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

* Backup Lamp Switch Replacement
* Underhood Electrical Center or Junction Block Replacement