B3445

DTC B3445

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 B3445
- Stop Lamp Circuit

Circuit/System Description

The body control module (BCM) supplies battery positive voltage to the center high mounted stop lamp (CHMSL) through the stop lamp supply voltage circuit when the brakes are applied. The stop lamp supply voltage circuit also supplies a signal to the powertrain control module (PCM) or engine control module (ECM) and the electronic brake control module (EBCM) for other functions, is a separate pin in the BCM connector, and is internally connected within the BCM.

Conditions for Running the DTC

* The battery voltage must be between 9-16 volts.
* The brake pedal must be applied.

Conditions for Setting the DTC

* When the BCM detects a short to ground in the stop lamp supply voltage circuit to the CHMSL.
* When the BCM never detects an open, indicating a BCM fault.
* When the BCM detects a short to ground in the stop lamp supply voltage circuit to another module.

Action Taken When the DTC Sets

The CHMSL will not operate.

Conditions for Clearing the DTC

* The current DTC will clear when the fault is no longer present.
* The ignition key must be cycled OFF and ON.
* A history DTC clears after 100 consecutive ignition cycles in which no faults have occurred.

Diagnostic Aids

* An internal short in the CHMSL may cause this code to set.
* A faulty CHMSL resistor may cause B3445 to set.

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) for Scan Tool Information

Circuit/System Testing

1. Disconnect the CHMSL.
2. Ignition ON, verify that a test lamp illuminates between the ground circuit terminal B and B+.

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

3. Verify that a test lamp does not illuminate between the stop lamp switch signal circuit terminal A and ground.

• If the test lamp illuminates, test the stop lamp switch signal circuit for a short to voltage.

4. Test the stop lamp switch signal circuit for a short to ground or an open/high resistance.
5. If all circuits test normal, replace the BCM.

Repair Instructions

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

Control Module References (Programming and Relearning)