Land Rover Repair: Sun roof, resistance ohms, using a multimeter

Question
Discovery 2 sun roof. The front sunroof will not open, but the rear opens easily. When the button for the  front sunroof is pressed there is a ticking sound like a clock. I am wondering if it is the ECU unit that needs replacing

Answer
Hi Roger,

rear works but not the front.  Sounds more like the motor apparatus. IF BCU was at fault, neither sunroof would move.

You'll have to look at the front motor gearbox using a multimeter and test if voltage & ohms are present during operation.

Pin No. Condition          Voltage Resistance, ohms
C0785-5 Ignition in position II, rear of front sunroof switch pressed +voltage

C0785-1 Ignition in position II, front of front sunroof switch pressed +voltage    < 0.5
C0784-8 Ignition in position II, sunroof fully closed          +V Batt
C0784-8 Ignition in position II, sunroof not closed          > 10,0000  

Better to test out the motor, sunroof assembly than just swap out sunroof ECU.  

TESTBOOK is used to test sunroof ECU.

Best of luck,
JohnMc