GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Yukon XL Denali 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC B3884

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

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

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

CHMSL Supply Voltage

B3884 00

1

2

--

  1. Stop Lamps Inoperative
  2. Stop Lamps Always On

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.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

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.
    2. ⇒ If a short between terminals is found, replace the CHMSL.
  2. Test the CHMSL supply voltage circuit for a short to ground.
    3. ⇒ If all circuits/connections test normal, replace the BCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  High Mount Stop Lamp Replacement
    •  Control Module References for BCM replacement, setup, and programming