B3445

DTC B3445

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B3445 00

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Center High Mounted Stop Lamp (CHMSL) Circuit

Diagnostic Fault Information






Circuit/System Description

Battery voltage is applied at all times to the body control module (BCM) from the BACKUP/STOP fuse located in the underhood fuse block. When the brake pedal is applied and the BCM receives a brake applied signal from the stop lamp switch. It then applies battery voltage through the CHMSL supply voltage circuit illuminating the CHMSL.

Conditions for Running the DTC

* Ignition ON.

* Brakes applied.

Conditions for Setting the DTC

The BCM detects a short to ground on the CHMSL supply voltage circuit when the stop lamps are commanded ON.

Action Taken When the DTC Sets

The BCM will deactivate power to the CHMSL.

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 Exterior Lights Schematics

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

Description and Operation

Exterior Lighting Systems Description and Operation Exterior Lighting Systems

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the X4 harness connector at the BCM.

2. Ignition ON, verify that a test lamp illuminates between the B+ 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. Ignition OFF, connect the X4 harness connector at the BCM and disconnect the harness connector at the CHMSL.

4. Test for less than 5.0 ohms between the ground circuit terminal B and ground.

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

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

6. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when pressing and releasing the brake pedal.

• 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. If all circuits test normal, test or replace the CHMSL.

Repair Instructions

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

* High Mount Stop Lamp Replacement Service and Repair

* Control Module References Control Module References for BCM replacement, setup, and programming