GM Service Manual Online
For 1990-2009 cars only

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 Lamps Relay B+

1

1

--

--

Backup Lamps Relay Control

B2545 00

1

1

--

Backup Lamps Control

1

1

1

--

Backup Lamps Ground

--

1

--

--

Backup Lamps Relay Ground

--

1

--

--

1. Backup Lamps Malfunction

Circuit/System Description

When the transmission range selector is placed in the REVERSE position, a signal is sent to the body control module (BCM). The BCM then applies voltage through the backup lamps relay control circuit energizing the backup lamps PCB relay. With the relay energized, battery voltage is applied through the left and right backup lamp fuses and the supply voltage circuits to the backup lamps.

Conditions for Running the DTC

Ignition ON. The backup lamps must be commanded ON.

Conditions for Setting the DTC

The BCM detects a short to ground on the backup lamps relay control circuit.

Action Taken When the DTC Sets

The BCM will deactivate the backup lamps for the remainder of the ignition cycle.

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 Verification

Ignition ON, place the transmission range selector in the REVERSE position. The backup lamps should illuminate.

Circuit/System Testing

  1. Ignition OFF, disconnect the X1 harness connector at the body fuse block.
  2. Connect a test lamp between the control circuit terminal 57 and ground.
  3. Ignition ON, command the backup lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
  4. 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.
  5. If all circuits test normal, replace the body fuse block.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Body Wiring Harness Junction Block Replacement
    •  Control Module References for BCM replacement, setup, and programming