Mk3 Golf Short Cicuit Somewhere - Battery Drain

[tsam19]

Has anyone had problems with the wiring in their mk3 golf or similar?

I'm experiencing a 'drain on the battery' for some reason, I think it may have something to do with the power windows in the rear.

I can now operate the power electric windows without the key in the ignition.

One of the rear windows does not operate at all now, just a clicking noise coming from behind the glove box area or near to it when the dash or door switch is pressed.

The other windows work as normal, but really there should be no power getting to the windows without the key in the ignition.

Any help would be welcome please.

[bora(ing) nick]

To check this, you should check the current flow over the fuses at the fuse box. The faulty circuit will be drawing more current than the rest. Make sure you do this with the ignition off, and car locked, (as if it were parked up).

You can then trace the wiring through.

Hope that helps!

[SammoVWT]

Behind the glovebox is the ignition coil with a nice cable coming out of it to your distributor, perhaps your ignition switch has worn out and its stuck in position one and maybe worn your ignition coil down also.

At least it could be the case for a petrol mk3, not sure on a diesel

[tsam19]

I changed the battery to a slightly lower amp rating (gone from 65 aph, to now 60 aph) - car still starts 1st time though no probs.

Now when I operate the passenger 'rear window switch' located on the dash (above the ashtray) the sunroof shuts (if its open) , but the rear window doesn't open???

All other switch selections are ok.

I think it could be a faulty switch??

Not sure though.

[Chrispythefish]

Hi matey, just remove your fuses 1 by 1 until your drain has gone, then go from there.
Sunroof shutting instead of windows etc sounds like a dodgy relay... I think their relay is shared. Not sure of the number but you could find out by doing the same as with the fuses, 1 by 1 until it stops working, if you don't have a manual to reference. Just remember where they go back, there are a few blank sockets on most models. I would think that the rear window you mention has possibly burnt out the relay by overloading it due to motor failure etc. You may want to disconnect that also beforehand and see if all is cured... it may be causing a short in the system and providing feedback to the other units via the relay! Stranger things have happened to me!
Changing the battery as little as that won't make any difference, it's only the potential output that you have dropped, not life expectancy.

Let us know how you get on.

Chris

[tsam19]

I only changed the battery because the original one had no power in it (11v)
I think it may have been on its way out for a while?

I kept the battery ratings similar to the drained one.

According to the manual wiring diagrams, fuse number 6 is the main one for the electric windows.

But there isn't a fuse for the sunroof, unless its part of the electric window circuit, in which case fuse number 6 should protect that circuit too.

As for the circuit diagram in the haynes manual, there doesn't appear to be a diagram for the electric windows only the sunroof.

Surely there would be only one relay that deals with all the electric windows & sunroof?

If there was only one & it was damaged wouldn't there be a problem with the rest of the electric window functions etc?

As I mentioned when I press the 'left hand' part of the dash 'rear electric window' switch the sunroof motor clicks away (shuts it if open), the window doesn't work.

But pressing the 'right hand' side works ok, as well as 'both' door switches.

The only other electrical issue I know of is the 'ashtray bulb' doesn't work when the main lights are on, even though the bulb has been renewed.

Hopefully it is just a faulty relay.

[Chrispythefish]

F14 is for the Windows in my wiring diagram, F4 is the sunroof. Thermal fuse/cutout for windows is relay 6 (top right), which could possibly do the sunroof as well. However manual not making a lot of sense... diagrams conflicting with fuse list. There is a diagram for windows, last one in manual. (Haynes 3097, not sure if you have this one)
Mine's a cabrio, so it's a bit different. Have you tried disco'ing the rear window motor and see if this cures the roof? You ought to take the switches out and run some elimination tests. Disco' each one and see what changes. Difficult to say without being there, but this is how we learn... so learning curve turning up for you!
So;
1. Take out relay 6, see if the roof still works. Do the windows work? (Shouldn't.) Put it back.
2. Take out fuse 4, check the roof doesn't work (if this is the sunroof fuse; if not, find which one is.) Check, when fuse is out and roof not working, that windows still work. Put it back.
3. Take out fuse 14, check that windows don't work, roof does. Put it back.

So you will have some elimination checks to work from... these will tell you how they are linked, if at all. If removing relay 6 disables both windows and roof then this may be the issue.

4. Take out switches in dash to see if any mods have been done. You may find someone has messed about with the wiring. Unlikely but possible. Do the same sort of thing as steps 1-3, unplug all switches, then plug each one in in turn and see what happens.

NB each time you disco' something, check to see that all other components/functions are still working. I know it's a pain in the butt... it will help you to get the picture...

My guess still lies with the relay being faulty, caused by the rear window overloading it. So you could replace motor and relay if you're not too fussed about cost (ok you probably are!); scrappers are quite cheap, plus rear window motors aren't used as much as front (unless you have a mad dog!). Suggest once you have done the check to disco' plug to window motor, if you think relay is dodgy, get another one, they're not expensive. Leave window disco'd. If everything is normal/cured then replace window motor... take the one out of the donor car first to practice... it's sooo much easier 2nd time round (not talking about women here... definitely!).

Ok let me know how you get on.
Cheers
Chris

[tsam19]

The VW in question was owned by the same family for 11years from showroom new - basically untouched or tampered with.

When I bought it everything worked as it should, this issue with the rear window has only just appeared in the last few months.

Initially the window stopped working, I though nothing of it & left it.

The car battery at the time was a maintainable one, which I forgot to maintain in the time I've owned the car & therefore more recently began not holding a correct charge.

On realising this error & I managed to replenish the electrolyte in the battery & funny enough the rear passenger window started to work again.

But it has gone back to its initial way & the battery mentioned above has been replaced due to its final expiry.

On changing the battery as mentioned earlier in my post to a slightly different rating, thats when I noticed the sunroof could be operated by the rear window switch on the dash.

I took out the switches on the dash only as explained, no mods have been done.

However I have not driven the car for a few days now & when I tried the left rear window switch with the sunroof open, it did nothing.

I will try the procedure you have mentioned over the weekend.

[Chrispythefish]

OK, still sounds like your rear window motor is at fault.
It's draining too much power, maybe it's just dirty and needs a lube.

[tsam19]

The replacement battery I put on the car last week has kept its power even though I've not driven the car for nearly a week now.

How can the one of the rear window motors be draining the battery when I'm driving or when I'm not & if the window is being opened or shut?

Its a regulated process, the motor will only move in 2 directions (open or shut), the load hasn't increased or decreased.

If the window motor was draining the battery there would be a constant operation of the window going up & down without me making any switch input.

There is no sound coming from the motor in question.

The rear windows only get opened every so often if that.

It will be one of the relays.