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 from the CHMSL/BCK-UP fuse through the instrument panel lamp control circuit and the interior backlighting components dim to the requested level.

DTC B2652 00 will set for the following conditions:

The BCM will not DIM or illuminate any I/P lamps supplied by the I/P lamps dimmer switch.

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

Scan Tool Reference

Control Module References for scan tool information

1. Ignition OFF, disconnect the X2 harness connector at the BCM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.

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

3. Ignition OFF, connect the X2 harness connector at the BCM.
4. Disconnect the X4 harness connector at the BCM.
5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.

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

6. Ignition OFF, connect the X4 harness connector at the BCM.
7. Disconnect the harness connectors at the following components.

•	Headlamp Switch

•	Instrument Panel Cluster (IPC)

•	Driver Window Switch

•	Driver Door Lock Switch

•	Outside Rearview Mirror Switch

•	Passenger Window Switch

•	Passenger Door Lock Switch

8. Ignition ON, clear the DTC with a scan tool.
9. Operate the system within the Conditions for Running the DTC and verify the DTC does not reset.

⇒	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 as current.

⇒	If the DTC resets as current, test or replace the component responsible for setting the DTC.

11. If all circuits test normal, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.