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theappliance
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Joined: Jan 19, 2011
Posts: 91
Location: near leicester

PostPosted: Sun Sep 20, 2015 6:05 pm Reply with quote

Hello all,

i would wager that everyone at some point in Audi coupe /S2 owner ship has had some sort of window fault...

I've had a couple recently and happily have fixed them both. Here is how for those of you experiencing similar, my findings hopefully give hope.


Drivers side motor.

Working up and down, then became randomly intermittent then it failed altogether. No nasty noises suggesting mechanical problems.

Process of elimination - check thermal fuse (you can insert a standard blade fuse for testing if you want) check power to plug in door handle (it was) send 12V down the paired connectors leading to the motor and find nothing happens. Remove motor, check on the bench and its dead. Remove spare motor from spare window regulator, bolt it in place in the original regulator and hey presto it all works. Apply lots of nice new grease and the window slides up and down faster than it has ever done. Suspect the old thick grease in the motor gearbox may have had something to do with the demise so that was cleaned out and replaced as well.


Passenger side motor.

Working up and down o.k, then intermittent then only working going down. It has been working only down for years now and the switch in the drivers door also didn't move it up. I had to take the switch out of the door to prevent girlfriend repeatedly sending window down only to find it won't go back up again. Laughing

Process of elimination - read lots of posts about it!
Get wiring diagram from Haynes manual
Remove parcel shelf to reveal the big relay (79FA404).
Change relay for known good one (made no difference).
Remove switches from both doors to reveal wires.
Check earth and continuity in switch - everything that should contact when pressing the switch did.
I drew up my own wiring diagram based on what i could see in the car, wrote wire colours on it and matched them up with lines. The haynes diagram to me was not all that clear. My own diagram made it easy to tick off the wires one by one from where they come from the relay to where they go into the switch. (You will find not all of the relay wires are involved in the window operation, one half of the big relay only has one wire involved - the blue and red power feed)
I tested continuity between both ends of each wire at relay and switch (all was good)
I tested continuity between each switch contact all seemed good.
I tested continuity between the passenger window switch in drivers door and passenger door (they are linked) and all was good.

Continuity is not the same as current carrying capacity...

I removed the passenger window motor to clean out the old grease and check whether it worked both ways when not in the regulator and not under load. It didn't.

I then did some switch swapping and found the passenger motor did work both ways when using the drivers window switch. LIGHTBULB MOMENT

My conclusion is that the window switches with age build up a high enough resistance to not work by allowing enough current to the motor to make it twitch, I say this as the contacts tested o.k with the multi meter and gave the impression it was all good. It wasn't. The contacts were however good enough to make the relay click occasionally as that could still be heard.

3 brand new switches on the way for 21 and I am as happy as Larry!
 
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Beerbelly
Site Admin
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Joined: Jun 03, 2010
Posts: 2397
Location: Sweden

PostPosted: Tue Sep 27, 2016 2:45 pm Reply with quote

Hello mate,
Were did you get the new switches from at the price?
I need 3 of the buggers
I think the original #was 893 959 855
New #number 4A0 959 855A
Cheers!

_________________
1994 AAN powered 80q (MTM hybrid turbo & ecu, Forge DV, 034 Highoutput Coil Packs, Wagner Tuning EM, 3\" turbo back SS exhaust system and a few other bits and pieces)
2012 VW Golf BMT Dark Label 2.0TDi 
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robert_95_S6
Nogsporter
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Joined: Jun 10, 2010
Posts: 501
Location: USA

PostPosted: Sat Oct 01, 2016 9:01 am Reply with quote

I've seen window switches get what I call 'zorched'. The contacts through use get a black residue sort of like a soot on them causing resistance.

Have taken the little buggers apart, folded some fine emery cloth in half and cleaned the contacts. They will work again. You have to be really careful taking them apart as there are spring loaded levers, balls and pins.

I don't think these were meant to be a serviceable item but it can be done. Use special care on the switch lock tabs, lift them ever so slightly to release them. Lift to hard and they will break, then the switch is junk.

Winter is fast approaching and I'll have time on my hands. Will try to put a 'work book' procedure together on how to do this.

Robert
 
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