Electric window short circuit

[RWMT]

Afternoon all,

My golf has developed an electrical fault this afternoon that has completely stumped me.

I went for a little drive earlier and, as it was hot, went to open my window but got nothing from either side.  I went straight to the fuse box and sure enough there was a blown fuse, however, and here is the tricky bit... with the ignition off I put a new fuse in, then turned the ignition on, fuel pump primes for a few seconds, and about a second after it stops bang goes the fuse without me trying the windows or swithing on any other electrical system within the car.

Everything was working perfectly last time I took the car out (Wednesday), so why all of a sudden the problem? And also, odd for it to short when I am not even asking the electric window circuit to do anything?

Background info:
Car - 1991 16v GTI
Fuse - 15 amp, in slot 14 (which according to the fuse box cover is "reversing lights")

Any light that anyone could shed on this would be much appreciated as I am at a loss for where to start my troubleshooting.

Thanks chaps 

[rubjonny]

1st thing, check the wires to the washer jets.  this fuse also does the heated elements, and the wires to them often snap and fall off. a short to earth here would blow zee fuse, or alternatively one/both of the jets could be knackered.  Then check the wires to the gearbox

If all that looks ok, get behind the fusebox and check the black wire to the electric window relay above the fusebox.  If that looks ok, then follow the wiring from the relay to the switches. Try disconnecting both switches and see if it still blows, then put them back in one at a time.

[RWMT]

Rubjonny, I could literally kiss you!

I popped open the bonnet and low and behold the wires of one of the washer jets had come adrift and fused themselves together.  However, I now seem to have only one window working...passenger side works fine, but I am getting nothing out of the driver's side.  I'll swap the switches over and some other basic stuff like that to see if it is just a simple fault.

Many thanks

[rubjonny]

have a look at the bulb in the switches, they should come on with the ignition. if one bulb is out this is a clue that the switch isnt getting power, though could just be a blown bulb 

[RWMT]

I have had a little rummage about and have determined that power is getting to the window motor in the driver's door, but it seems unable to turn.  When the switch is pressed the motor makes a slight clunk/clicking noise (it sounds like the motor taking up a very slight touch of slack in the mechanism before reaching the sticking point) but no movement.  I have tested the wires supplying the motor for power and (from memory) they were reading about 12.6 volts.  Incedentally, at the switch it was about 14.95 volts, so i don't think that a lack of power is the issue.

Is the mechanism prone to jamming and is there an easy fix?

[rubjonny]

yeah sounds liek the motor has jammed. try holding switch down and giving the door a proper hard slam shut 

if that doesnt help you'll probably need a new regulator

[bomp]

I recently made a non working motor work again, by scrubbing rust and grime that was collected on the metal parts (of the window motor itself) with a bit of P400 wet and dry, and washed it all off with WD40.  I also gave the copper parts, where the brushes touch the motor, a little clean with P400 aswell, so the brushes have a good contact. The inside of the motor cover also had scrub with a dremel type tool with a wire brush fitting, then a load of thinners shaken inside it to get rid of old grease/dirt/dust. I then smeared new grease onto the top of the motor where it fits onto the cover and tightened everything back up. Tested the motor on a battery, and it went like a good'n

You can do that by just undoing the two screws that hold the motor cover onto the regulator, and pull the cover off.  But you will have to take the window reg out of the door to do a proper job.

If your fealing brave take the regulator apart and clean the old crap out of that too. But its one of them "need three hands jobs" and most definately a bench vice at hand, as the springs on the cables are an utter cow to put back in without one.

[RWMT]

Well I tried the good old "if it doesn't work, then hit it" approach, but after several solid slams of the door I have had no joy. 

Thanks for the info bomp, I am hesitant to chuck out what was a perfectly good regulator until a day or so ago so think I might have a go at freeing the old one up before tracking down a replacement.  Motor seems to be working fine (I think), just the reg jammed from what I can make out.

Speaking from experience, do you think that it is more trouble than its worth trying to clean out the old regulator?  What sort of ballpark figure are we looking at for a replacement?  If it's a lot then I will take on the challenge of doing it myself!

[bomp]

It's worth cleaning out the reg, to get the 20 years or so of crap that's slowly built up in there. It's usually the thick clogged up black grease inside them that slows the motor down too.

If your handy DIY wise, then do it, you just need patience.  The most awkward part of putting them back together was holding the cables on the centre reel while putting the cap onto the reel and trying to hold the main bit of plastic that the cables go through, without the cables coming undone again.

But I did learn (from trial) that when putting the cables back into main white plastic section, you put one cable in first, with the spring held in the right place, then put the cover on and fully tighten one screw on that side only, then loosley put the other 4 screws on, but giving enough room to slide the spring back on the other cable.

All this ^ probably wont make sense until you get your hands dirty anyways, but there's no harm trying to fix something for nothing.

I got a full working reg & motor from the scrappy last week for £15 but expect to pay upto £25. On a certain "scene" forum they go for double that.

[RWMT]

Like you said, I am sure it will all make sense once I have the reg in pieces!

I secretly quite enjoy the challenge of trying to fix these things myself, after all that is part of the reason that I bought the car.  I will give it a shot when I have a spare afternoon. 

Sounds like you have developed a pretty sound strategy, many thanks for the all of the advise.