GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

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

DTC Descriptor

DTC B2625 00: Display Dimming Pulse Width Modulation (PWM) Output Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

LED Indicator Dimming Supply

B2625 00

B2625 00

B2625 00

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Circuit/System Description

When the interior lamps dimming switch is activated, a variable voltage signal is applied through the instrument panel lamps dimmer switch signal circuit to the body control module (BCM). The BCM then applies a variable voltage signal through the LED indicator dimming supply circuit to the components on the circuit.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The BCM receives a ground signal on the LED indicator dimming supply circuit.

Action Taken When the DTC Sets

The BCM cease attempt to dim or illuminate the LED indicator lamps.

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

Interior Lights Dimming Schematics

Connector End View Reference

Component 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, headlamp switch to PARK, vary the interior lamp dimming switch from dim to full bright. The LED lamps should dim and then become full bright.

Circuit/System Testing

  1. Ignition OFF, park lamps OFF, disconnect all the LED indicator dimming supply circuit lamp components on the circuit. Verify DTC B2625 does not set.
  2. If the DTC resets, test for a short to voltage, short to ground, or an open in the LED indicator dimming supply voltage circuit. If the circuit/connections test normal, replace the BCM, driver door switch, and passenger door switch as applicable.
  3. Reconnect each component one at a time and test for the DTC B2625.
  4. If the DTC resets, replace that particular component.
    If the DTC does not reset, replace the BCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    • Refer to the appropriate replacement procedure for the component causing the condition.
    •  Control Module References for BCM replacement, setup, and programming