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 has overviews of all diagnostic categories.

DTC Descriptor

DTC B2545 02

Backup Lamps Circuit Short to Ground

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Backup Lamps Control	B2545 02	1	2	-
1. Backup lamp always OFF 2. Backup lamp always ON

Circuit/System Description

When the transmission is placed in reverse gear, the engine control module (ECM) 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 battery voltage to the backup lamps. The backup lamps are permanently grounded. Once the driver moves the gear selector out of the reverse position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the backup lamp control circuit.

Conditions for Running the DTC

Reverse gear engaged.

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

The appropriate backup lamp is inoperative.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

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 information on diagnostic tools

Circuit/System Verification

Ignition ON, perform the Backup Lamps test. The backup lamps should be ON/OFF.

Circuit/System Testing

1.	Ignition OFF, disconnect the appropriate harness connector at the appropriate tail lamp listed below:

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E42L Tail Lamp Assembly - Auxiliary Left

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E42R Tail Lamp Assembly - Auxiliary Right

2.	Test for less than 5 Ω between the appropriate ground circuit harness connector terminal listed below and ground:

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E42L Tail Lamp Assembly - Auxiliary Left harness connector terminal F

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E42R Tail Lamp Assembly - Auxiliary Right harness connector terminal F

•

If greater than the specified value, test the appropriate ground circuit for an open circuit/high resistance.

3.	Connect a test lamp between the appropriate control circuit harness connector terminal listed below and ground:

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E42L Tail Lamp Assembly - Auxiliary Left harness connector terminal D

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E42R Tail Lamp Assembly - Auxiliary Right harness connector terminal D

4.	Command the Backup Lamps test 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 K9 Body Control Module.

6.	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 Body Control Module.

7.	If all circuits test normal, replace the appropriate backup lamp.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Tail Lamp Replacement

•	Control Module References for information on BCM replacement, setup, and programming