B2545
DTC B2545
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)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 GMLAN 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 lamp control circuit to the left rear fuse block. The left rear fuse block distributes the battery voltage to the backup lamps and inside rearview mirror. The backup lamps are permanently grounded at G402. Once the driver moves the gear selector out of the REVERSE position, a message is sent by the TCM via GMLAN 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 the BCM detects a short to ground or an open/high resistance in the backup lamps control circuit or the BCM 4 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.
* You issue a scan tool CLEAR DTCs command.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)
Circuit/System Testing
1. Ignition OFF, disconnect the joint connector at the left rear fuse block.
2. Connect a test lamp between the backup lamp supply voltage circuit terminal S17 and ground.
3. 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, test the BCM 4 fuse voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Disconnect the harness connector at the inside rearview mirror.
5. Verify that a test lamp does not illuminate between the inside rearview mirror backup lamp supply voltage circuit terminal 9 and B+.
• If the test lamp illuminates, test the control circuit for a short to ground.
6. Connect the harness connector at the inside rearview mirror.
7. Ignition ON, verify that a test lamp illuminates between the inside rearview mirror backup lamp supply voltage circuit terminal S15 and B+.
• If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the inside rearview mirror.
8. Disconnect the harness connector at the inoperative backup lamp.
9. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms of resistance between the inoperative backup lamp ground circuit terminal B and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
10. Ignition ON, verify that a test lamp does not illuminate between the backup lamp supply voltage circuit terminal S16 and ground.
• If the test lamp illuminates, test the backup lamp control circuit for a short to voltage.
11. Connect the harness connector at the inoperative backup lamp.
12. Connect a 10-A fused jumper wire between the backup lamp supply voltage circuit terminal S16 and B+. Verify the backup lamps are activated.
• If the backup lamps do not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the inoperative backup lamp.
13. If all circuits test normal, test or replace the left rear fuse block.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Backup Lamp Replacement (Service and Repair)
* Inside Rearview Mirror Replacement (UE1) (Inside Rearview Mirror Replacement (UE1))Inside Rearview Mirror Replacement (DD7, DD8) (Inside Rearview Mirror Replacement (DD7, DD8))
* Control Module References (Programming and Relearning)for BCM replacement, setup, and programming