B2556

DTC B2556

Circuit Description

The instrument panel (I/P) dimmer switch is a potentiometer. The dash integration module (DIM) determines the control setting based on the voltage from the I/P dimmer switch. The intensity of the of the backlighting is adjustable when ever the park lamps are on. The intensity of the vacuum florescent displays are only adjustable when it is night and the park lamps are active.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2556 Passenger Compartment Lamp Control Circuit Range/Performance

Conditions for Running the DTC

The DIM is powered.

Conditions for Setting the DTC

The I/P dimmer switch voltage is less than 0.09 volt or greater than 4.80 volts.

Action Taken When the DTC Sets

Set dimming level to 100 percent full brightness for all displays.

Conditions for Clearing the DTC

The DIM does not detect a voltage that is less than or greater than the predetermined value during the diagnostic self test.

Test Description

Step 1 - Step 9:

Step 10 - Step 15:

The numbers below refer to the step numbers on the diagnostic table.
3. This step tests for the proper operation of the circuit in the high voltage range.
4. This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
5. This step tests for a short to ground in the 5-volt reference circuit.