audi-bahston

The new Alt is in... again, thanks to all on this forum.

Car = 200 20v

I've had this problem since I bought the car a little bit over a year ago. When I start the car I get three lights coming on... Battery, Brake and Anti-lock and the voltage meter would read kinda low around 10. Revving the RPM's past 3 would make the lights go out and the voltage would spike to normal and the dash would be illuminated regardless of the Headlights being on or off.

I put in a crappy used alternator and did some work on the Instrument Cluster and I still had the same symptoms. The only change was that revving the engine had no affect on the lights but flicking the headlight switch on and then back off would make those lights go out and the voltage spike to normal. This time the IC would only illuminate when it was supposed to... when the HL's were on.

Recently the lights would come on as normal and revving the engine or flicking the lights had no affect. The car eventually wouldn't charge and I changed the Alt out with a Bosch Re-manned unit.

I started the car after the R&R and I'm back to scenario #1. Revving the RPS's past 3 would make the lights go out and bring the voltage meter spiking to normal levels and the dash is always lit.

I looked in the Bentley (27.17) and it has a trouble-shooting procedure for the exact opposite problem. I've searched the forums and looked on the internet but have not found anything. Could this be something screwed up in the IC? A faulty ground somewhere in the Alt wiring? What is my car trying to tell me?

Any ideas or trouble-shooting tips would be much appreciated.

TIA

-Kev

V8QinNJ

IIRC.. there is a circuit that unless complete (that runs thru the dash), will give you those issues.

The Alt exciter isn't seeing that there is a demand, so the VRU stay's "Off".

Sorry I can't be more specific, but I only read about it, no hands on. Maybe someone will chine in here. You can "jump the circuit" by takign the charging lead from the Alt's output and looping a small wire back onto the exciter.

HTH..

Scott - '90 V8Q x2

squidix9

What is happening is that the exciter isn't seeing enough voltage until you get the rev's up. "Somewhere" between the exciter (blue wire on newer B3's) and the battery is a somewhat bad connection.

The last post I saw somewhere (can't remember what forum) the writer found a circuit on the back of the IC that was bad and resoldering over it fixed the problem.

What you need to do is find out where it is. With a voltmeter on the exciter terminal read the voltage. You'll need a Bentley to follow the wiring diagram. Either start at the exciter end of the battery end and trace it backwards or forwards till you find out where you're losing it and fix the faulty connection.

I've got this same problem on the rally Coupe, but I haven't had the time to fix it. So...I rev it up to around 3k till it charges then I'm good to go. Yeah, it's on the to-do list to get done.

V8QinNJ

I found the diagram here:
<a href="http://www.humanspeakers.com/audi/altpix.htm">Click Me</a>


It thru the oil pressure light circut..go figure..

HTH.

-Scott

audi-bahston

Is the exciter wire on the battery end the little wire that is looped around the bolt that tightens the positive battery cable?

Just wondering if this is a fault that will cause more problems or something that I'm gonna have to live with if I can't trace it down in the wiring?

squidix9

But it could be anywhere in between or in the IC even.

You can do a quick check and run a wire directly to the battery and see if it helps like V8in NJ said.

Kneale Brownson

The exciter wire comes, as V8qinNJ notes, from the instrument cluster. Most of the Type 44, I believe, have a "blue" exciter wire starting at the alternator and running through the IC to--I think--the fuse box. If it doesn't run to the fuse box, it ends at the IC. It's pretty common for the alternator end of that wire to get corroded just like the corrosion that fouls up the little wire that tells the starter solenoid to operate. I've replaced a couple feet of that wire beginning at the alternator on one of my cars because it was turning all green inside.