Posting for a friend that is prepping his car for SCCA in NARRC ITE..

We're trying to wire the killswitch. He has a late 1.8T VW motor in a 84 Scriocco.

"The problem with the altenator is that it takes it's feed for the exciter wire directly from the battery cable wire from the back of the car. I will asssume I have to cut all power to the main feed cable before the altenator? Not sure how to isolate it completely from the system so the car shuts off when switched."