• | 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. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
VEH BCK/UP Fuse B+ | B2545 00 | B2545 00 | -- | -- |
Backup Lamps Control | B2545 00 | 1 | 1 | -- |
Backup Lamp - Left Ground | -- | 1 | -- | -- |
Backup Lamp - Right Ground | -- | 1 | -- | -- |
Backup Lamp Relay Ground | -- | 1 | -- | -- |
1. Backup Lamps Malfunction |
When the transmission is placed in the REVERSE position, the transmission control module (TCM) sends a serial data message to the body control module (BCM). The message indicates that the gear selector is in the REVERSE position. The BCM applies voltage to the backup lamp relay control circuit energizing the backup lamp relay coil. With the relay coil energized, the switch contacts close allowing battery voltage to flow through the VEH BCK/UP fuse to the left and right backup lamps. The BCM also supplies voltage the to inside rearview mirror via the backup lamp relay control circuit for automatic day/night operation. Once the driver moves the gear selector out of the REVERSE position, a serial data message is sent by the TCM requesting the BCM to remove voltage from the backup lamp control circuit.
Exterior Lighting Systems Description and Operation
Control Module References for scan tool information
⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block.. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for BCM replacement, programming, and setup |