I wired up my car for haltech over the winter and decided not to use any control features for my alternator and just give it the one hot wire to keep it constantly on. I noticed the other day when getting close to redline on the track my voltage was all the way down to 12.9. Once I slowed down it was up to 13.8. But also while cruising if I turn on the coolant fan or anything voltage will drop a little. Is this a bad alternator or should I wire up the ecu to control it?

 

Yes, you need to wire up the alternator control.

 

Alright I’ll look into that do you know what pin on the alternator needs to go to the ecu. I was always told all I needed was the IG pin to get constant power and it would work like normal but clearly it does not.