ever since ive had my SC400(about 4 months) I have CEL and a trac OFF light that both come on, havent got the car scanned yet and its obd1. Sometimes I would start my car its not on and sometimes its already on. once I start driving it comes on and stays on. Comes and goes. I don't feel any power difference or anything. If I turn it off and on again it would go away but comes back. Also to note that has some sort of voltage issue. Whenever I give it any throttle the lights like headlights and interior lights brighten, press on the brake or use turn signals. it dims and comes right back. I have already replaced the alternator, battery, battery thermals. Its got to be some ground but I don't know which one. Maybe that CEL has something to do with it? IDK

 

A CEL question without checking codes is rather pointless...

The dimming lights could be any of the main grounds (there's one on the frame, right near the battery), the cables themselves, or the battery terminals.

 

Ive checked almost all the grounds and they seem fine to me, I have replaced my battery terminals, but I am thinking its the cables itself. this all started when the previous owner installed a radio, amp,speakers,alarm system. Which i have mostly fixed.