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 Descriptors

DTC B2610 01 : Instrument Dimming Bulb Output Circuit High Voltage
DTC B2610 02 : Instrument Dimming Bulb Output Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
I/P Dimmer Switch Signal | B3600 03 | B3600 03 | B3600 07 | --
Headlamp Switch Backlighting Control | 1 | 1 | 1 | --
LED Backlight Dimming Control | B2610 02 | 1 | B2610 01 | --
Headlamp Switch Low Reference | -- | 1 | -- | --
Headlamp Switch Ground | -- | 1 | -- | --
1. Interior Backlighting Malfunction

### Circuit/System Description

The instrument panel (I/P) lamp dimmer switch is incorporated into the headlamp switch assembly. The I/P 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 instrument panel cluster (IPC) provides a low reference signal and a 12-volt 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 IPC. The IPC interprets the signal and applies the dimmed voltage to the I/P lamps supply voltage circuit and the interior backlighting components dim to the requested level. Ground for the I/P dimmer switch is provided at the headlamp switch low reference circuit through the IPC.

### Conditions for Running the DTC

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

• | Park lamps ON.

### Conditions for Setting the DTC

#### B2610 01

The DTC will set when the IPC detects a short to voltage in the LED backlight dimming control circuit.

#### B2610 02

The DTC will set when the IPC detects a short to ground in the LED backlight dimming control circuit.

### Actions Taken When the DTC Sets

The IPC will not dim or illuminate any indicators supplied by the LED backlight 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. With a scan tool clear the DTC.
2. Ignition OFF, disconnect the harness connectors at the following components fed by the LED backlight dimming control circuit.

• | Transmission range selector indicator

• | Dome lamp - front

• | Dome lamp - center

• | Hazard switch

• | HVAC control module

• | Sunroof control module

3. Operate the vehicle within the conditions for running the DTC and verify the DTC does not reset.

⇒ | If the DTC resets, test the LED backlight dimming control circuit for a short to voltage or a short to ground. If the circuits test normal, replace the IPC.

4. 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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Dome Lamp Replacement

• | Front Seat Heater Switch Replacement

• | Automatic Transmission Range Selector Lever Replacement

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