For the past few weeks I have lost power door locks, windows, wipers, sunroof, etc. when the ambient temperature has dropped into the 30's. This morning I had a chance to find out why. I followed the procedure written by Javier(?) and all was well with the grounds and power at the fuses, relays and modules under the rear seat.

I took the general module out of its case and warmed the board with a hairdryer. When I reinstalled it everything worked fine. How do I diagnose what solder joints might be cracked in order to repair it?