Is there a diagnostic procedure for determining whether the ignition switch is bad? And I don't mean throwing parts at the car to see if it fixes the problem.

Car's been starting and running fine. Last Friday, it would occasionally not do anything when I turned the key to the cranking position. Releasing the key and trying again would solve the problem. Then it just stopped functioning altogether. Now the crank position won't work at all anymore. Everything seems to work fine (I can push-start the car), but I can't get the starter to work.

There's a REALLY funny diagram in the service manual. It shows a picture of the ignition switch terminals, with the following table underneath:

15 - Terminal 15
30 - Terminal 30
50 - Terminal 50
50b - Terminal 50b
75 - Terminal 75
86s - Terminal 86s
P - Park

How brilliantly useless!

 

alldata shows the same thing with no help on testing procedures which they normally do

 

Check the terminals that are tagged as output (terminal 30 I believe is one). Worth the key turned there should be voltage at those pins. Honestly though the switches are known to die, they're around $27 shipped - just replace it. If it's a fix, great. If not its troubleshooting time and chances are you've averted a future failure.

 

Thanks! You're right, terminal 30 should light up when I turn the key, based on a youtube video I just found. However, the guy in the video went to all the trouble of taking out the A/C compressor and reaching for the same wire at the starter itself rather than checking for voltage at the switch... seems like such a waste of time. I'll check at the switch.

If it is bad, I wonder if there's a way to "fix" it until a new one gets here (ie. bend some pins on the inside of the switch casing). There's really no slant to my driveway, and it's a bitch to push-start in the cold of winter.

 

Don't know if you can apply a simple fix to your current switch... but... I replaced my ignition switch around 136k miles with an aftermarket one. Around 146k miles that one started acting up, doing what you described. Sometimes I'd have to turn the key to START 15 times before it would finally start! Put in another ignition switch last weekend and that fixed it like there was no problem.

 

it's weird, it started working fine again yesterday. Starts every time now.

I've ordered a new ignition switch and will replace it as soon as it arrives. Hopefully it solves my problem.

 

For mine, it started acting up for a couple weeks. Then I ordered a new one. After a couple days, the old one worked flawlessly for about a week, and started misbehaving yet again. I replaced it a few days after that.

These things are so pesky and finicky!

 

Wouldn't be so bad if there was some hint as to what's going wrong. Back when this happened last summer, I at least had a hint what to look for because there was an error logged in the Central Locking module (it was due to the hood latch switch). But this time, there's no indication of an error, no pattern to give a clue, nothing... it could be the ignition switch, or it could be the clutch switch, or it could be the starter solenoid, the list goes on and on.

Audis are so mysterious...