Possible causes, elimination, notes

Diagnosis conditions 

No control module fault stored.

No fault with supply voltage (5 volts).

Short to B+/ Short to ground 

1. Remove sun sensor.
2. Remove plug connection from sun sensor.
3. Connect voltmeter on sleeve side to pin 2 (negative) and pin 3 (positive).

   Switch on ignition.

   Display: approx. 4.5 - 5 volts

   If 0 volts is displayed, check wiring to the heating/air-conditioning control A 12 and B 18 for continuity.

   Check wiring to the heating/air-conditioning control B 18 for short to ground.

   NOTE: The wiring to the heating/air-conditioning unit is routed via two plug connections.
   If the wiring is OK, replace the heating/air-conditioning control.
4. Connect ohmmeter to sun sensor pins 2 and 3.

   Sun sensor not in darkness

   Display: approx. 1.3 Mohm

   Sun sensor in darkness

   Display: approx. 240 kohm