AudiWorld Forums - 1991 200TQ Alternator issues

Hi guys,

Been trolling around this forum since I picked up the car and have learned a ton about these beasts. I've searched high and low and have found conflicting information about replacing the wire from the charging system idiot light on the dash to the exciter on the alternator. The situation is this:

1991 audi 200TQ which up until 2 weeks ago ran like a champ. Noticed that the volt gauge showed low voltage so decided that a higher amp alternator wouldn't hurt and that my current setup was dying so ordered one up and got it installed.That's were the issues started. Had the replacement alternator bench tested and all is well according to two different tests. Voltage measured at back of alternator on the bench indicated 14.8V consistently. In the car is another story.

I've tested continuity from battery to + alternator lead (strong 12.4v). Checked and cleaned all of the grounds on the alternator and engine to frame. Where things start getting weird is when I test the resistance on the exciter wire as outlined in this article http://audiurquattro.de/ralf/infos/pdf/Alternator.pdf.
I'm reading resistance in the 850ohm range and up. So i'm assuming an issue from the idiot light to the alternator. All of this suffice to say I can't find anything about "replacing the printed circuit" as mentioned. Anybody done this before?

Thanks for the help!