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 diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B2652 00: Passenger Compartment Dimming 3

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+, BCM X2 Terminal 2

B2652 00

B2652 00

--

--

I/P Lamps Control

B2652 00

2

1

--

1. Interior Backlighting Does Not Dim

2. Interior Backlighting Inoperative

Circuit/System Description

The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the instrument panel lamp control circuits illuminating the components listed below.

    • Hazard Switch
    • I/P Cluster
    • Power Window Switches
    • Sunroof Switch
    • Garage Door Opener Transmitter

Conditions for Running the DTC

    • The ignition is ON.
    • The headlamps or park lamps ON.

Conditions for Setting the DTC

The BCM detects a short to ground on the instrument panel lamps control circuit.

Action Taken When the DTC Sets

The BCM does not attempt to illuminate the instrument panel lamps.

Conditions for Clearing the DTC

A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, command Incandescent Dimming ON with a scan tool. The Incandescent Relay Command parameter should display On and the Incandescent Dimming should illuminate.

Circuit/System Testing

  1. Ignition OFF, disconnect the X2 harness connector at the BCM.
  2. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.
  3. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuits listed below for a short to ground.
    • Instrument panel lamp control circuit terminal 3 X2
    • Instrument panel lamp control circuit terminal 3 X6
  4. Ignition OFF, connect the X2 harness connector to the BCM.
  5. Disconnect the harness connectors at all components fed by the BCM control circuits listed below.
  6. • Instrument panel lamp control circuit terminal 3 X2
    • Instrument panel lamp control circuit terminal 3 X6
  7. Ignition ON, clear the DTC with a scan tool.
  8. Operate the system within the Conditions for Running the DTC and verify the DTC does not reset.
  9. If the DTC resets, test the control circuits for a short to ground. If the circuits test normal, replace the BCM.
  10. Reconnect each component one at a time and verify that the DTC does not reset.
  11. If the DTC resets, test or replace the component responsible for setting the DTC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Hazard Warning Switch Replacement
    •  Sunroof Switch Replacement
    •  Garage Door Opener Replacement
    •  Control Module References for BCM replacement, setup, and programming