B3884

DTC B3884

DTC Descriptor
DTC B3884 00 Center High Mounted Stop Lamp (CHMSL) Circuit

Diagnostic Fault Information
Perform the [Diagnostic System Check - Vehicle Diagnostic Information] prior to using this diagnostic procedure. Diagnostic System Check - Vehicle Diagnostic Information






Circuit/System Description
When the brake pedal is applied, the brake pedal switch normally closed contact signal circuit voltage is interrupted to the body control module (BCM). The BCM then applies a voltage to the CHMSL supply voltage circuit to the center high mounted stop lamp (CHMSL).

Conditions for Running the DTC
^ The ignition is ON.
^ The stop lamps must be commanded ON.

Conditions for Setting the DTC
The BCM detects a short to ground in the CHMSL supply voltage circuit when the stop lamps are commanded ON.

Action Taken When the DTC Sets
The CHMSL does not illuminate.

Conditions for Clearing the DTC
^ The conditions for setting the DTC are no longer present.
^ A history DTC clears after 100 malfunction-free ignition cycles.
^ The BCM receives the clear code command from the scan tool.

Circuit/System Verification
Ignition ON, press the brake pedal. The CHMSL should illuminate.

Circuit/System Testing
1. Disconnect the CHMSL and test for internal shorts between all terminals of the CHMSL assembly.
^ If a short between terminals is found, replace the CHMSL.

2. Test the CHMSL supply voltage circuit for a short to ground.
^ If all circuits/connections test normal, replace the BCM.

Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure. Diagnostic Repair Verification - Vehicle Diagnostic Information
^ [High Mount Stop Lamp Replacement]
^ [Control Module References] for BCM replacement, setup, and programming Programming and Relearning