CrazyPete

Good day fellow audi enthusiasts!

My poor a4 is having some trouble recently. I drove her to work no problem and return that night to find my headlights, wipers high beams, turn signals, horn and cabin fan suddenly dont work. I can still get hazards and I can still pull back on the stick to get passing flashers....which is how I drove it home.

I diligently read the forums and replaced the ignition switch with an intermotor part...no change. I then popped out the 370 load reduction relay and replaced that.....no difference. Additionally, sometimes, when I power on the car, the wipers will give a little jerk then die again.

What is next on the list to look for? I am worried that this might start being big ticket items.

turbo510

The encouraging thing is early A4s are pretty simple in that part of the electrical system. For starters you'll want to remove the steering column shroud so the connectors can be checked for voltage. I've got my schematic (for a '96) at home so if I don't see that you have solved it this evening, I'll offer an opinion.

CrazyPete

Thank you for your quick response!

I'll take the shroud off tonight and give it a whirl. What should I be looking for? Which pin is the troublemaker?

CrazyPete

Oh... sorry....the car in question is a 1999 (early year) a4 quatrro tiptronic. It looks like the ignition switch was white instead of black so it might have already been replaced before and the load reduction relay was already the 370 instead of 213 so that might have been replaced before too.

The only thing non factory about thic car is a tipchip and a giac stage 1 ecu.

turbo510

It looks to me like your problem is likely at the ignition switch. Everything you mentioned, except horn and headlights, that isn't working is fed from the circuit "X", the load-reduction relay's power output. This relay is turned on by terminal 75 of the ignition switch. With the ignition turned to the "on" position, you should have power at the terminal marked "75". You might have to partially pull off the connector to probe the pin, and if there is power, then check this circuit at the light switch and/or load-reduction relay. There should be two yellow/black wires at or near the ignition switch connector (however I'm looking only at a schematic). The larger of the two goes to the light switch, the smaller to the load-reduction relay's coil terminal.

CrazyPete

Thanks! I'll check it out tonight!

Have you ever heard of replacement switches being bad out of the box? That was my other thought

turbo510

Some of the guys who are real Mechanics could answer that, though it's probably not common. Maybe the the ignition switch connector has a damaged receptacle or bad wire crimp at the "75" position.

CrazyPete

The car seems to be exhibiting some delightful behavior in relation to these pins.

I have the following:
30 Brown 12v
30 Red 12v
15 black 12v
50 blue 3v
50B Red/blk zero volts
75 yellow/blk 12v

Now here is the cool thing....if I push on the 50B red/blk, I get 12v at the "75" position and everything works but the lights. When I hit the lights, the 75 goes dead and so does everything else....no matter how hard I push or wiggle the 50B until I take the key out and put it back in.

No codes on the engine and the fuses look good, including the 40 and 50 amp ones I just discovered under the dash.

turbo510

It sounds more and more like a switch problem. Pushing on "50B" (do you mean on the brass terminal sticking out of the switch body?) must be helping somehow a very marginal connection at "75". When you turn on the lights, the current arcs and burns the contacts.

I would assume that this is a mechanical thing because electrically there's no reason why Term 50 would affect Term 75. Terminal 50B goes to the alternator and alt warning light, and terminal 50 goes to the starter solenoid.

At this point you may want to just take out the switch and either swap in a new one, or in a pinch pry off the cover and clean-up the contacts with a narrow strip of #1000 aluminum oxide paper and rubbing alcohol. I've done mine like that and it works fine. You've got to take the steering wheel off though.

CrazyPete

I got it! The number 30 wire hanging out near the 75's actually had a loose connection that was melting the casing and the molten plastic was interfering. It was subtle and hard to see. There was no "brown" wire.....it was supposed to be red! =O

Thank you so much for your help! The audi is back on the road!