I bought a 2006 XC90 with a damaged UEM. It had a short circuit on the X-supply line. I managed to repair the module and everything is working fine now, except the sunroof. The siren and key fob are also working. It looks like the CAN bus and K-line are ok.

The only DTC I get is UEM-0020 (rear view mirror signal missing), which is probably not related to the sunroof.



Here's what happens when I operate the sunroof switch:
Position 1 (front auto): not working
Position 2 (front): not working
Position 3 (back): not working
Position 4 (back auto): WORKING, the glass goes all the way back to the fully open position
Position 5 (tilt up): after 5 seconds keeping the button pressed, the glass moves 1cm (3/8") frontwards and stops
Position 6 (close): the glass moves rearwards if the the button is kept pulled, until it's fully open

VIDA is reporting all switch positions as "activated" when engaged/pressed. I am also able to roll the glass all the way front and back, using VIDA's manual activation functions.

I tried all known methods to reset the UEM and calibrate the sunroof. None worked. I also tried disconnecting the siren.

Maybe there's something wrong somewhere else in the circuit, because of that DTC, or maybe it just needs a calibration trick?
Does anyone have a clue on that problem?

*** UPDATE ***
I decided to rescan the car with VIDA and now it is throwing some more DTCs, which for some reason were not showing before:
UEM-0051 Unknown position of sunroof
UEM-0057 No control signal from optical sensor 2 when the relay is activated and the motor is supplied with power
UEM-0065 The signal for forwards movement of the sunroof is activated too long
UEM-0066 The signal for backwards movement of the sunroof is activated too long
UEM-0068 The sunroof TILT signal is activated too long

 

I hate to answer my own questions, but at least I hope it helps someone else.
It turned out that the the sunroof module (SRM) was not properly installed. Someone has serviced it before me and has not installed it correctly.
One of the ends of the SRM has a T notch that must be placed between the two cables that run across the ceiling. One of the cables, I believe, is the water drain line. The other one connects to a "mouse-like" wheel inside the SRM. This wheel has two sensors, and they inform the position of the glass to the module.
When reinstalling the module, be sure the notch is in between the two cables.
After that, I recalibrated the sunroof as per manual and now everything is working.