B2622

DTC B2622 or B2623

Diagnostic Instructions

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

DTC Descriptor
DTC B2622
- Dimming Display Pulse Width Modulation (PWM) Input Circuit Low

DTC B2623
- Dimming Display Pulse Width Modulation (PWM) Input Circuit High

Diagnostic Fault Information





Circuit/System Description

The body control module (BCM) receives a variable voltage signal from the instrument panel (I/P) dimmer switch requesting to illuminate the I/P controls illumination lamps to a desired intensity. When this occurs, the BCM directly sends a variable voltage based on the I/P dimmer switch position through the I/P lamps supply voltage circuit to the I/P controls illumination lamps.

Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

B2622

When the BCM receives an I/P controls illumination lamp request signal and the I/P lamps supply voltage circuit is shorted to ground.

B2623

When the BCM is not receiving an I/P controls illumination lamp request signal and the I/P lamps supply voltage circuit is shorted to voltage.

Action Taken When the DTC Sets

The I/P controls illumination lamps will not operate or are always on.

Conditions for Clearing the DTC

* This DTC will clear on current status after the condition for setting the fault is corrected.
* A history DTC will clear after 100 consecutive ignition cycles without a fault present.

Reference Information
Schematic Reference

Interior Lights Dimming Schematics (Interior Lights Dimming Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Interior Lighting Systems Description and Operation (Interior Lighting Systems Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inoperative interior backlighting lamp.
2. Verify that a test lamp illuminates between the listed component ground circuit and B+.

* Accessory switch terminal 13
* Hazard switch terminal B
* HVAC control module terminal C
* Rear window wiper/washer switch terminal A
* Radio terminal B5 X1
* Sunroof switch terminal C
* Headlamp switch terminal 3

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

3. Ignition OFF, park lamps ON, verify that a test lamp illuminates between the listed control circuit terminal and ground.

* Accessory switch terminal 12
* Hazard switch terminal A
* HVAC control module terminal D
* Rear window wiper/washer switch terminal D
* Radio terminal B4 X1
* Sunroof switch terminal B
* Headlamp switch terminal 6

• If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the BCM.
• If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, replace the component with the inoperative backlighting.

Repair Instructions

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

* Accessory Switch Replacement (Service and Repair)
* Hazard Warning Switch Replacement (Service and Repair)
* Headlamp Switch Replacement (Service and Repair)
* Rear Window Wiper and Washer Switch Replacement (Service and Repair)
* Sunroof Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM, HVAC control module, or radio replacement, programming, and setup