Front door wiring loom replacement and locks.

[DavidTdi]

On the 2008 125k miles A3 I've just bought for my daughter it has the not uncommon (I've learned from reading past threads) front door locks which don't open with the plip. Also the wiring has several wires in the drivers door shut area with broken insulatIion and a couple where the copper is just starting to break.... plus the passenger side has just two with insulation cracked but copper inside still unbroken.

I'm taking the door cards off today to see if the fault is the same as this guy mentions and if his repair would work for me. If not I'll get new locks. Regarding the wiring I wonder if anyone has used this or any other loom repair kits as I would prefer to get any joins away from the area of bending in the door shut??

 https://www.ebay.co.uk/itm/274077641017?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

All ideas appreciated.

 

 

 

[cliffcoggin]

I've not heard of the repair kits. On the face of it they seem like a good idea having multi-strand wires and silicone insulation for flexibility, however the quality of manufacture is going to be critical, and that's something you can not assess in advance. Perhaps buy one for testing before committing to more.

[DavidTdi]

Yep agreed only needs to be a bit poorly made and it will create even more problems some time down the line. It's £40 too which is about a third of a new OE loom which will be fit and forget for the rest of the life of the car.

[cliffcoggin]

Do let us know the outcome of the kit if you get one. It appears to be a common problem so it would be good to know of a home fit solution.

[DavidTdi]

Will do. I'm fighting the door lock internals at the moment... if that repair works both sides I'll regard it as a saving over replacing with new ones enough to almost justify a new harness.

[DavidTdi]

This turned out to be a challenging repair.

On the passenger side with not too bad condition wiring in the door shut area I tried the lock motor repair as in the first post video but no improvement so probably either the potted electronics or one of the potted micro switches had failed. A £25 breaker's yard replacement lock of the same part number but from a 2012 car worked immediately it was fitted and I just added extra insulation to the loom in the door shut.

On the drivers side the motor repair as in the video worked... for about 10 test lock/unlock cycles then stopped when I found the wiring in the door shut had actually parted. Thought long and hard but wanting this to be a "once and done" repair I forked out the £145 for a new Audi door loom that side. It was very fiddly to feed inside the door around the window slide as I was really wary of straining it.

When I pulled the loom plug from the door pillar socket the socket came loose and fell down in the door pillar. So I had to remove the inside footwell trim to push it back in place and the work out exactly how the purple clip worked to hold it back in place.  Turned out you pull the purple clip backwards to release the socket from the pillar... which I'd done by accident... and then while holding the socket in place from inside the car slide the purple clip forward to lock it in place again.

Images below of the new loom, the purple clip and of the small hole to use a long screwdriver through to hold the socket in place while you re-engage the purple clip.

Note the purple clip shouldn't be moved to release the plug from the socket... there is a hidden tab on the front of the socket... you can just reach a finger round and spring that in.

 

 

[DavidTdi]

Annoyingly the new loom didn't make the lock work so I guessed my lock repair hadn't worked well and ordered a 2011 lock from a breakers... but that displayed exactly the same faults and codes. So I wasted ages stripping the two locks I now had... cleaning up the motor commutators... greasing the moving parts and even re-assembling them in various combinations of parts from the two locks mixed together... but still no luck.

Images of the locks in various stages of stripdown.

 

[DavidTdi]

One thing kept coming to mind. On the passenger side which was easily fixed with a used lock assy the only code was for the lock... but on the driver's side it showed an additional code for the door module which apparently can happen but caused me to wonder if that module had failed. 

When doing the loom swap I'd had the plugs out of the door module and all looked OK but I decided to double check. With a bright torch and very close look I noticed three of the pins on the top right socket of the module were more grey than the bright shiny silver of the rest. Scraping these pins with a tiny sharp screwdriver produced fine grey deposits and then switch cleaner brought the pins back to shiny. 

Plugged in the replacement used lock and it worked straight away... as did the original one I'd overhauled. Cleared the codes and they remained gone.

Good result in the end but it was amazing how such a tiny film of discolouration could mess things up so badly.

Image of door module.

 

[DavidTdi]

The door cards are actually really easy to take off and despite being a tight space the lock assy comes out OK... apart from one thing that I couldn't work out for a while and didn't want to break... the yellow and black plastic clip that holds the door handle rod to the lock assy.

Image below for detail. When in place in the door you need to push the yellow tab away from you with a screwdriver and at the same time hook the black bit to rotate towards you. The rod is still slightly gripped but can be flicked out.

[Steve Q]

Thanks for a very detailed repair guide David. Glad you got sorted in the end even if it did give you the mess around. 

Cheers 

 

 

 

 

 

 

 

 

 

 

[cliffcoggin]

It's remarkable how little corrosion is needed to spoil the operation of some electronic systems, and how much effort is needed to overcome it. I admire your perseverance David.

[DavidTdi]

>>> remarkable how little corrosion is needed to spoil the operation of some electronic systems

And so it has proved.

 I had a mobile locksmith out the other day to supply and program a new second key which is a story in itself. However when going multiple times to lock/unlock as well as the new remote being erratic the fault as detailed above returned whereby the drivers door needed the key to unlock when the rest of the doors worked OK on remote.

I took the door panel off assuming it would be the lock failed mechanically again but turned out to be the pins I'd scraped clean on the door module were again giving a high resistance. Seems once they corrode and you scrape them back you get to an imperfect surface that re-corrodes??

Anyway cleaned the pins again and it's back working. Will price up a new module against a used one that may or may not have pin corrosion.

 

[cliffcoggin]

1 hour ago, DavidTdi said:

I took the door panel off assuming it would be the lock failed mechanically again but turned out to be the pins I'd scraped clean on the door module were again giving a high resistance. Seems once they corrode and you scrape them back you get to an imperfect surface that re-corrodes??

It's common in such situations for pins to be plated, sometimes even with gold, to resist corrosion. Once the plating is removed corrosion can return much faster, though a few weeks seems unusually rapid in this case. Are you sure water isn't getting in or condensing there?

[DavidTdi]

Yep water was my first thought but no the door is bone dry inside as I'd expect as the car has been garaged and its only ten days since I cleaned the pins. It's a bit frustrating as this car was bought for my daughter with two weeks to fettle it but she's collected now and taken it back to her area 100mls away. She is aware the fault may return but I hope it works for at least the month or two before we see her and the car again when I may fit a new module.

[JonA3]

Hi all, having problems with the door locking on my 2005 A3, I have just replaced the lock mechanism and the problem remains, which is the door won't open with the fob ( battery replaced ) and does not open manually with the key, electric window, mirrors working fine, just cannot lock the car, any ideas please?

[cliffcoggin]

31 minutes ago, JonA3 said:

Hi all, having problems with the door locking on my 2005 A3, I have just replaced the lock mechanism and the problem remains, which is the door won't open with the fob ( battery replaced ) and does not open manually with the key, electric window, mirrors working fine, just cannot lock the car, any ideas please?

Given that you have revived an old thread about faulty wiring to door locks, can we assume you have checked the wiring and the connectors?

[JonA3]

Hi, thanks for your reply, not entirely, I replaced the lock mechanism with a new one as this seemed to be a common fault, I will check the wiring at the door hinge area, but was wondering if there is any other  module or control unit that needs checking, kind regards.