[s-cars] dash light wire?

[steve powers]

Hi!

I'm installing some gauges in my A-pillar and need to run a signal to
dim the lights. I'm hoping someone has done this and can tell me what
color wire I'm looking for in the car harness and where I might find it.
With lots of luck I can intercept this signal near the relay panel below
the steering wheel.

(My Audi manuals are complete, except for electrical - they're
pre-Bentley)

Thanks!

Steve Powers