For 1990-2009 cars

### 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

### DTC Descriptor

DTC B2545 00: Backup Lamps Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Backup Lamp Relay B+ | 1 | 1 | -- | --
Backup Lamp Relay Control | 1 | 1 | B2545 00 | --
Backup Lamps Control | 1 | 1 | 1 | --
Backup Lamp Ground - Left | -- | 1 | -- | --
Backup Lamp Ground - Right | -- | 1 | -- | --
1. Backup Lamps Malfunction

### Circuit/System Description

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 ground 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 from the BACKUP LP fuse to the left and right backup lamps. Once the driver moves the gear selector out of the REVERSE position, a message is sent by the TCM via serial data requesting the BCM to remove ground from the backup lamp relay control circuit.

### Conditions for Running the DTC

• | Battery voltage must be between 9-16 volts.

• | Backup lamps commanded ON.

### Conditions for Setting the DTC

DTC B2545 00 will set when the BCM detects a short to voltage in the backup lamp relay control circuit.

### Actions Taken When the DTC Sets

When DTC B2545 00 is present, the backup lamps will not operate.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists.

• | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

### Reference Information

#### Schematic Reference

Exterior Lights Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exterior Lighting Systems Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Ignition OFF, disconnect the backup lamp relay.
2. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
3. Command the Reverse Light Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the backup lamp relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Underhood Electrical Center or Junction Block Replacement

• | Relay Replacement

• | Control Module References for BCM replacement, setup, and programming