B2556

CIRCUIT DESCRIPTION
The interior lamp rheostat is a potentiometer. The Instrument Panel Integration Module (IPM) determines the control setting based on the voltage from the interior lamp rheostat. The IPM monitors the voltage in the instrument panel lamps dimmer switch signal circuit every 150 milliseconds.

CONDITIONS FOR RUNNING THE DTC
The ignition switch is in the ON position.

CONDITIONS FOR SETTING THE DTC
The interior lamp rheostat is less than 12 Counts or greater than 244 Counts on 3 consecutive tests.

ACTION TAKEN WHEN THE DTC SETS
Set dimming level to full brightness for all displays.

CONDITIONS FOR CLEARING THE DTC
The IPM detects that the interior lamp rheostat is between 12 and 244 Counts.

TEST DESCRIPTION

Steps 1-5:

Steps 6-15:

The numbers below refer to the step numbers on the diagnostic table.
3. Tests for the proper operation of the circuit in the high voltage range.
4. 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. Tests for a short to ground in the 5 volt reference circuit.