B2627

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 feedback 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 less than 0.2 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 IP dimmer switch short to ground condition must be corrected.

TEST DESCRIPTION

Steps 1-4:

Steps 5-16:

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.
11. Tests for a short to ground in the twilight sentinel delay signal circuit of the twilight delay switch. A short to ground may set DTC B2627 and DTC B2642 depending position of the IP dimmer switch.