Just have to trace the circuit board to the red light. I think it is more of a diod though. With juice coming from the battery to the alt it goes through the key and the dash and excites the alt and also lights the red light up. Once the alt is excited and juice starts flowing out instead of in the light goes out as the volts coming out of the alt is higher then what the battery has so the current reverses. I also want to say there is a 3 prong deal on the circuit board on the dash that is common to burn out. I just can't remember if it works with the alt or not.
Shade Tree Mechanic
"I'm too shady to know anything"
1981 Rabbit car-4 door, 1.9 TD aaz, 5 spd
1981 Caddy VW truck-Topper with it
2004 Golf-2 inch lift, Q-loader stage 1 tune
Originally Posted by rmchambers
I really had no idea that VW dealerships were so awful to go to, they sound like undertakers cos everything that goes in there winds up dead.