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+ Supply | 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 Verification
- Ignition ON, with the transmission in park or neutral the backup lamps should not illuminate.
- Shift the transmission into reverse, the backup lamps should illuminate.
Circuit/System Testing
- Ignition OFF, disconnect the park neutral position or backup lamp switch connector.
- Ignition ON, connect a test lamp between the listed control circuit terminals and ground.
- Connect a test lamp between the listed voltage supply circuit terminals and ground. The test lamp should illuminate.
- Connect a 15 amp fused jumper wire between the listed voltage supply circuit and backup lamp control circuit. Both backup lamps should illuminate.
- If all circuits test normal, test or replace the park neutral position switch or backup lamp switch.
| • | Park neutral position switch terminal 10 - with M30 |
| • | Backup lamp switch terminal B - with MA5 |
| ⇒ | If the test lamp is illuminated, test the listed backup lamp control circuit for a short to voltage. |
| • | Park neutral position switch terminal 11 - with M30 |
| • | Backup lamp switch terminal A - with MA5 |
| ⇒ | If the test lamp does not illuminate, test the appropriate voltage supply 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 both backup lamps are not illuminated, test the backup lamp control circuit for a short to ground or an open/high resistance. |
| ⇒ | If one backup lamp is not illuminated test the appropriate control and ground circuits for an open/high resistance. If the circuits test normal, replace the appropriate backup lamp. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
