Seldum

I had the same problem two months ago, and was able to fix it myself.

Theres two things which might trigger the problem you described (to my knowledge):

1: A disfunctional microswitch "quick opener" on window tailgate
2: Corrosion/electrical problem with the wirering near the henges of the tail gate.

The solution to fixing the first problem is to replace the microswitch. I did this myself using a guide I found on this site I believe. I'm not very handy at all so its a cheap and easy fix.

The solution to fixing the second possible problem is a bit more difficult. But theres also guides to do this. You will have to take a look at the right hendge and the wires which goes through there.

I would start out by changing the microswitch, it's easy, cheap and might fix your problem.

Sorry for the bad spelling :/