[s-cars] Re: inop tachometer/need new tach?

[Mark Strangways]

Sounds typical of a bad ground weld.
Audi (VW) like to make theses nice welded ground connections all over the 
place.

I have traced the ground path from the tach, it does ground the brake 
warning light, and leaves the IC thru connector T26a ( 26 PIN GREEN) pin 
number 11.
The ground then goes to ground connection 81 which is in instrument panel 
wiring harness.
Try to bring a NEW solid ground point to the IC connection T26a (green) just 
before the connector. Splice it in or use a needle to pierce the wire 
insulation, then ground that well. If you problem goes away, then look at 
that ground connection to see where it breaks. I would not just re-ground 
that point, as you could eventually leave other stuff ungrounded later.

Mark S