B2628

CIRCUIT DESCRIPTION
The IP dimmer switch is a potentiometer. It is powered by the HVAC control module. The HVAC control module determines the level of dimming desired based on the voltage from the IP dimmer switch. The HVAC control module converts the IP dimmer switch feed back voltage to a digital signal and puts it on the Class II communication bus.

CONDITIONS FOR RUNNING THE DTC
The HVAC control module must be powered.

CONDITIONS FOR SETTING THE DTC
The feedback voltage is greater than 4.8 V for more than 200 milliseconds.

ACTION TAKEN WHEN THE DTC SETS
The dimming level is set to full brightness for all displays.

CONDITIONS FOR CLEARING THE DTC
The HVAC control module does not detect a voltage greater than the predetermined value during the diagnostic self test.

TEST DESCRIPTION

Steps 1-4:

Steps 5-15:

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 IP dimmer switch signal circuit is shorted to voltage.
5. Tests for a short to ground in the 5 volt reference circuit.