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 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

I/P Dimming Voltage Reference

B1395 03, B3600 03

B1395 03, B2652 00, B3600 03

B1395 07

--

Courtesy Lamp Voltage Reference

B2615 00, B2615 02

B2615 00, B2615 04

B2615 00, B2615 01

--

LED Dimming Voltage Reference

B2610 00, B2610 02

B2610 00, B2610 04

B2610 00, B2610 01

--

LED Indicator Dimming Volage Reference

B2625 00

B2625 00

B2625 00

--

Dome Lamp Switch Signal

2

2

2

--

Left Front Door Open Switch Signal

3

3

3

--

Left Rear Door Open Switch Signal

4

4

4

--

Right Front Door Open Switch Signal

3

3

3

--

Right Rear Door Open Switch Signal

4

4

4

--

Stop Lamp Switch Signal

B1395 03, B3600 03

--

--

--

Dome/Reading Lamp Control

B2615 00

B2615 00

--

--

Dome/Reading Lamp Supply Voltage

1

1

--

--

Exterior Lamps Illumination Supply Voltage

5

5

5

--

Inadvertent Power Control

5

5

5

--

I/P Lamps Dimming Control

B2652 00

B2652 00

B2652 00

--

Dome/Reading Lamp Low Control - Driver Door

--

1

--

--

Dome/Reading Lamp Low Control - Passenger Door

--

1

--

--

Exterior Lamps Low Reference

--

5

--

--

I/P Dimmer Switch Ground

--

2

--

--

LH Vanity Mirror Courtesy Lamp Ground

--

1

--

--

Overhead Console Courtesy Lamp Ground

--

1

--

--

Rear Dome Lamp Ground

--

1

--

--

RH Vanity Mirror Courtesy Lamp Ground

--

1

--

--

1. Courtesy Lamps Malfunction

2. Dome Lamp Switch Malfunction

3. Door Open Switch Malfunction - Front

4. Door Open Switch Malfunction - Rear

5. Exterior Lamps Malfunction

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

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 Testing

  1. Ignition OFF, disconnect the harness connector at the inoperative component.
  2. Connect a test lamp between the listed LED dimming control circuit terminal and ground.
  3. • IP multifunction switch X88/Z88 w/UD7/XA7 terminal 8
    • IP multifunction switch Z75 w/UD7 terminal 4
    • IP multifunction switch Z75 w/XA7 terminal 7
    • 4wd mode switch terminal 4
  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.
  5. 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.
  6. If all circuits test normal, test or replace the inoperative component.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Accessory Switch Replacement
    •  Control Module References for BCM replacement, setup, and programming