B2652

DTC B2652

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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/System Description

The body control module (BCM) applies a 12-volt reference voltage through the headlamp and panel dimmer switch 12-volt reference circuit to the headlamp and panel dimmer switch. When the dimming switch is placed in the desired position, the dimmed voltage setting is applied from the headlamp and panel dimmer switch through the instrument panel (I/P) lamp dimming switch signal circuit to the BCM. The BCM then applies the dimmed voltage to the I/P lamp dimming control circuit and the components on the circuit.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The BCM receives an open, voltage, or ground signal on the I/P lamp dimming control circuit.

Action Taken When the DTC Sets

The I/P lamps are not illuminated.

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 and park lamps ON, vary the headlamp and panel dimmer switch from dim to full bright. The I/P lamps should dim and then become full bright.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the affected component.
2. Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and battery voltage.

* Rear window switch terminal F
* Headlamp switch terminal 8
* Transfer case shift control switch terminal 6
* Sunroof switch terminal 5
* Folding seat switch terminal 4
* Power liftgate open/close switch terminal C
* CJ3 HVAC control module terminal 2

^ If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the listed backlighting control circuit terminal and ground.

* Rear window switch terminal B
* Headlamp switch terminal 7
* Transfer case shift control switch terminal 5
* Sunroof switch terminal 3
* Folding seat switch terminal 5
* Power liftgate open/close switch terminal B
* CJ3 HVAC control module terminal 1

4. Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.

^ If the test lamp is always off, test the control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.

^ If the test lamp is always bright, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the affected component.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Headlamp Switch Replacement (Cadillac) Headlamp Switch Replacement (Except Cadillac)
* Rear Side Door Window Switch Replacement
* Sunroof Switch Replacement
* Rear Seat Recliner Switch Replacement - Overhead Console
* Rear Seat Recliner Switch Replacement - Lock Pillar Trim