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 |
|---|---|---|---|---|
BCK/UP Fuse B+ | 1 | 1 | -- | -- |
Backup Lamps Control | 1 | 1 | 1 | -- |
Backup Lamp - Left Ground | -- | 1 | -- | -- |
Backup Lamp - Right Ground | -- | 1 | -- | -- |
1. Backup Lamps Malfunction | ||||
Circuit/System Description
The BCK/UP fuse in the underhood fuse block supplies B+ to the normally open park/neutral position (PNP) switch used in a vehicle equipped with an automatic transmission or the backup lamp switch if equipped with a manual transmission. When the driver places the gear select lever in the REVERSE position, the switch closes and the current flows through the switch to the backup lamps. The backup lamps are grounded at G350 and G340.
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
- 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 park/neutral position switch - with M30 or the backup lamp switch - with MA5.
- Ignition ON, verify that a test lamp illuminates between the appropriate control circuit terminal listed below and ground.
- Connect a 15 amp fused jumper wire between the appropriate control circuit terminals listed below. Verify the backup lamps illuminate.
- If all circuits test normal, test or replace the park/neutral position switch or the backup lamp switch.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| • | Park/neutral position switch terminal 11 - with M30 |
| • | Backup lamp switch terminal A - with MA5 |
| ⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. |
| • | Park/neutral position switch terminal 11 and terminal 10 - with M30 |
| • | Backup lamp switch terminal A and terminal B - with MA5 |
| ⇒ | If the backup lamps do not illuminate, test the appropriate control circuit terminal listed below for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the inoperative backup lamp. |
| • | Park/neutral position switch terminal 10 - with M30 |
| • | Backup lamp switch terminal B - with MA5 |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
