Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Backup Lamp Switch B+ -- Manual Transmission | 1 | 1 | -- | -- |
Park/Neutral Position Switch B+ -- Automatic Transmission | 1 | 1 | -- | -- |
Backup Lamp Control | 1 | 1 | 1 | -- |
Backup Lamp - Left Ground | -- | 1 | -- | -- |
Backup Lamp - Right Ground | -- | 1 | -- | -- |
1. Backup Lamps Malfunction | ||||
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
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
Backup Lamps Malfunction - Automatic Transmission
- Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
- Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal G and ground.
- Connect the harness connector at the inoperative backup lamp.
- Ignition OFF, disconnect the harness connector at the backup lamp switch.
- Ignition ON, verify that a test lamp illuminates between the control circuit terminal A and ground.
- Verify that a test lamp does not illuminate between the control circuit terminal B and ground.
- Connect a 15-amp fused jumper between the control circuit terminal A and the control circuit terminal B. Verify the backup lamps illuminate.
- If all circuits test normal, test or replace the backup lamp switch.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | 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. |
Backup Lamps Malfunction - Manual Transmission
- Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
- Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal G and ground.
- Connect the harness connector at the inoperative backup lamp.
- Ignition OFF, disconnect the harness connector at the PNP switch.
- Ignition ON, verify that a test lamp illuminates between the control circuit terminal 11 and ground.
- Verify that a test lamp does not illuminate between the control circuit terminal 10 and ground.
- Connect a 15-amp fused jumper between the control circuit terminal 11 and the control circuit terminal 10. Verify the backup lamps illuminate.
- If all circuits test normal, test or replace the PNP switch.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
