For 1990-2009 cars

### 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 02: Display Dimming Pulse Width Modulation (PWM) Output Circuit Short to Ground

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
I/P Dimmer Switch Signal | 1 | 1 | 1 | --
Indicator Dimming Control | B2625 02 | 1 | -- | --
Park Lamp Control | -- | 1 | -- | --
I/P Dimmer Switch Low Reference | -- | 1 | -- | --
1. Interior Backlighting Malfunction

### Circuit/System Description

When the headlamp switch is placed in either the HEAD or PARK position, ground is applied to the park lamp signal circuit to the body control module (BCM). The BCM responds by applying ground to the park lamp relay control circuit. This energizes the park lamp relay coil causing the relay switch contacts to close allowing battery voltage to flow to all of the park, tail, license, marker lamps, interior ambient lighting, and to the BCM. The BCM receives the voltage from the park lamp relay indicating the park lamps are ON. The BCM uses this signal to command the interior backlighting ON and OFF. The instrument panel (I/P) lamp dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The I/P dimmer switch provides a voltage signal that will increase as the brightness of the lights are increased and decrease as the brightness of the lights are decreased. The body control module (BCM) provides a B+ voltage signal and a low reference to the I/P dimmer switch. When the I/P dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the I/P dimmer switch through the I/P dimmer switch signal circuit to the BCM. The BCM interprets the signal and applies the dimmed voltage to the indicator dimming control circuit and the interior backlighting components dim to the requested level.

### Conditions for Running the DTC

• | Battery voltage must be between 9-16 volts.

• | Park lamps ON.

### Conditions for Setting the DTC

DTC B2625 02 will set when the BCM detects a short to ground in the indicator dimming control circuit.

### Action Taken When the DTC Sets

When DTC B2625 02 is present, the BCM will not illuminate the interior backlighting supplied by the indicator dimming control circuit.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists.

• | 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 Testing

1. Ignition OFF, disconnect the harness connectors at the following components:

• | Automatic transmission control indicator

• | Door lock switch - driver

• | Door lock switch - front passenger

• | Fog lamp switch

• | Hazard Switch

• | Heated seat switch - driver

• | Heated seat switch - passenger

• | HVAC control module

• | Instrument panel cluster (IPC)

• | Outside rearview mirror switch

• | SWC BKLT fuse

• | Traction control switch

• | Turbo boost gage - with LNF

• | Window switch - driver

• | Window switch - front passenger

2. Ignition ON, with a scan tool clear the DTC and operate the vehicle within the conditions for running the DTC and verify the DTC does not reset.

⇒ | If DTC B2625 02 sets as current, test the indicator dimming control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

3. Reconnect each component one at a time and verify that the DTC does not reset as current after each component is reconnected.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Door Lock Switch Replacement

• | Fog Lamp Switch Replacement

• | Front Side Door Window Switch Replacement - Left Side

• | Front Side Door Window Switch Replacement - Right Side

• | Hazard Warning Switch Replacement

• | Transmission Floor Shift Control Indicator Lamp Replacement

• | Turbocharger Pressure Power Indicator Replacement

• | Driver or Passenger Seat Heater Switch Replacement

• | Power Mirror Switch Replacement

• | Control Module References for BCM, HVAC control module, or IPC replacement, setup, and programming