Cruze

DTC B3600

The instrument panel dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The body control module (BCM) supplies a 12 V reference to the backlight dimmer switch, which is part of the headlamp switch. When the backlight dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage to the LED dimming control circuit to all related interior lamps, illuminating them to the desired level of brightness.

The ignition is ON.

The Instrument Panel lamps are not illuminated.

A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

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

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, cover the ambient light sensor, vary the interior lamp dimming switch from dim to full bright. The instrument panel lamps should dim and then become full bright.

1. Ignition OFF, disconnect the harness connector at the S30 Headlamp Switch.
2. Ignition ON, test for 11.8-12.2 V between the 12 V reference circuit terminal 1 and ground.

⇒	If greater than the specified range, test the 12 V reference circuit for short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

⇒	If less than the specified range, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

3. Verify the scan tool Incandescent Dimming parameter is less than 10%.

⇒	If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the 12 V reference circuit terminal 1. Verify the scan tool Incandescent Dimming parameter is greater than 90%.

⇒	If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

5. If all circuits test normal, test or replace the S30 Headlamp Switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.