B2545

DTC B2545

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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/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 battery voltage to the backup lamps and inside rearview mirror. The backup lamps are permanently grounded at G302. 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 battery voltage from the backup lamp control circuit.

Conditions for Running the DTC

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

DTC B2545 00 will set when one of the following conditions exits:

* The BCM detects a short to ground in the backup lamps control circuit.
* The BCM detects a short to ground or an open/high resistance in the CHMSL/BCK-UP fuse voltage supply 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.

Circuit/System Testing

With DD6
1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Verify a test lamp illuminates between the B+ supply circuit terminal 4 and ground.

^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Connect the X4 harness connector at the BCM.
4. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
5. Connect a test lamp between the control circuit terminal 9 and ground.
6. 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.

^ 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.

7. Connect the harness connector at the inside rearview mirror.
8. Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
9. Ignition OFF, exterior lamps OFF, test for less than 10.0 ohms between the ground circuit terminal B and ground.

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

10. Connect a test lamp between the control circuit terminal A and ground.
11. 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.

^ 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.

12. If all circuits test normal, test or replace the inoperative backup lamp.

Without DD6
1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Verify a test lamp illuminates between the B+ supply circuit terminal 4 and ground.

^ If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Connect the X4 harness connector at the BCM.
4. Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
5. Ignition OFF, exterior lamps OFF, test for less than 10.0 ohms between the ground circuit terminal B and ground.

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

6. Connect a test lamp between the control circuit terminal A and ground.
7. 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.

^ 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.

8. If all circuits test normal, test or replace the inoperative backup lamp.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Backup Lamp Bulb Replacement
* Inside Rearview Mirror Replacement.