GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 LaCrosse 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B2545

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: Backup Lamps Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Backup Lamp Supply Voltage

B2545

1

2

--

Backup Lamp Ground

--

1

1

--

1. Backup Lamps Inoperative

2. Backup Lamps Always On

Circuit/System Description

When the transmission range selector is placed in the REVERSE position, a serial data message is sent from the powertrain control module (PCM)/engine control module (ECM) to the body control module (BCM). The BCM then applies voltage to the left and right backup lamps through the backup lamp supply voltage circuit.

Conditions for Running the DTC

The ignition is ON. The backup lamps are commanded ON.

Conditions for Setting the DTC

The BCM detects a short to ground on the backup lamp supply voltage 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 gear selector in the REVERSE position. The backup lamps should illuminate.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the right backup lamp.
  2. Test for less than 10 ohms between the ground circuit terminal B and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal A and ground.
  4. 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.
    5. ⇒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. Ignition OFF, connect the harness connector at the right backup lamp. Disconnect the harness connector at the left backup lamp.
  6. Test for less than 10 ohm between the ground circuit terminal B and ground.
    7. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect a test lamp between the control circuit terminal A and ground.
  8. 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.
    9. ⇒If the test lamp is always ON, test the control circuit for a short to voltage.
    ⇒If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.
  9. If all circuits test normal, test or replace the applicable backup lamp bulb.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Backup Lamp Bulb Replacement
    •  Control Module References for BCM replacement, setup, and programming