C4 100/A6 (1992 - 1997)
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Replacing ignition switch
Posted by: Ben1 (5412) on 2010-07-06 00:05:24
In Reply to: ELECTRICAL, ENGINE AND BODY posted by Brdman* on 2009-03-17 03:12:31

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This is a common point of failure in all C4s due to an under-engineered switch. There were recalls on this part. Luckily it's a pretty easy fix. Writeups follow:


How to replace the ignition switch (On 1992-1997 Audi C4 A6/100s) (by snowman 92):
I didn't remove the steering wheel like the Bentley says, but it may be easier. To me, it's not worth dealing with the finicky airbag system anyway.

So here's how you do it:

- First disconnect your battery. Get your radio code 'cause it'll go into SAFE mode when you hook up the battery again.

- Lower the steering wheel and pull it as far back as it will go.

- Remove two screws holding the bottom ledge of the dash plastic on. This is just beneath the instrument cluster (IC), one screw on each side of the steering wheel.

- Pull the left side of the trim piece back and then slide the whole piece towards you and to the left.

- Remove three screws holding down the IC.

- Cover your steering column with a clean rag or old t-shirt to prevent scratches or ugly marks.

- Jimmy the instrument cluster back towards you and out of the hole. Probably need to start with the right side.

- Pull IC back and then rotate the right side vertical so that it is standing nearly straight up, wedged between the steering wheel and the dash. This gives you room to work.

- Follow the ignition switch (where you stick the key) back behind the dash and you'll see a pink or purple clip on the portion you have to change out. Look at the new switch you bought to see what it looks like.

- Before removing the switch, there are two screws that hold it in place. However, these screws are covered by some thread locking compound and need to be cleared before you can remove the switch.

- I used a ~4mm wide flathead screwdriver to dig 'em out AND to remove them. I coulda sworn I was just stripping the top of the screw, but it turned out that the screw is really tough and that I was stripping the aluminum threads it sat in--which is no big deal.

- Once you clear the little RED thread locking stuff from the screws, back them out so that a couple threads are sticking out. You don't need to remove them.

- Now the switch should slide backwards. Play with the switch (with wire harness still attached) until you can get the female end looking directly at you. This isn't easy as there's another thick cable that confines it to that small area behind the lock cylinder of the ignition.

- Pull the harness off. It's ok to GENTLY use a screwdriver to help pry the harness off.

- Place the new switch in the harness.

- Place the assemly back in the mounting bracket with the two thread-locked screws. This takes some patience and good aim. I moved the routing of the wires so that WHEN this switch breaks, I can easily switch-out-the-switch.

- Tighten down the two thread-locked flathead screws. I don't think it's important to put any more locking compound here. Your choice, but if you're car all of a sudden doesn't start, you know why...

- You can either check operation of switch (start the car) or go to the next step.

- Put the IC back in; three screws hold it in.

- Put the trim piece back in; two vertical screws hold it in.

- Voila!


Another ignition replacement writeup, this one by DaveInSaltLake:


I noticed this FAQ doesn't really have an entry for replacing the ignition switch, so I thought I'd share the results of my spending a couple of hours sifting thru search results. And since I don't know the prevailing feeling about reposting text written by other members, I'll just post links to their posts.

http://forums.audiworld.com/a6100/msgs/40096.phtml use with the next link covering instrument cluster removal: http://forums.audiworld.com/a6100/msgs/22219.phtml




http://forums.audiworld.com/a6100/msgs/47727.phtml (more info on removing the IC)

I haven't done this R&R yet, and so don't have any personal input. It appears the instructions may vary for different models and model years.

This obviously isn't exhaustive...feel free to add more.

Edit: OK, NOW I have something to add.

Given: 1992 Audi 100 CS, automatic transmission
New black switch
A handful of write-ups from this board
My very user-UNfriendly Bentley CD-ROM

Process: Pulled the IC most of the way, only unplugged 2 connectors and that gave me enough room to manuever. Pulled the knee bolster panels, which turned out to be completely unnecessary. Forget screwing around with the Bowden Cable Cover, as Bentley calls it, I didn't need to do it. Moved the relay that's obviously in the way, unplugged the connector from the back of the switch, loosened the two little set screws...out came the switch.

Key elements to reassembly--note proper orientation of new switch before sticking it into the dark void. I couldn't get the connector back on after I had the switch installed so I pulled it back out, plugged in the connector, and then stuffed back into the dash and into the end of the lock cylinder....that worked just fine for me.

I have to wonder if the high failure rate for these switches is due to people forcing the switch to turn when the steering wheel is locked. I'm in the habit of jiggling the steering wheel enough to let the key turn easily.

And, I don't see how a heavy keyring could wear the plastic ignition switch. The switch is about 4 or 5 inches behind the dash on the end of a long metal lock cylinder. I don't see any way for the weight to be transferred to the plastic parts.

my 2 cents...

This link is dead, but in case it works in the future, you can try it:

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