I am new to Mustangs always been a chevy mopar guy. Anyways I have a charging system issue with my 1988 coupe 5.0. I put a new alt, new alt plug and battery in the car due to the part store telling me all tested bad. Prior to my purchase the car sat for who knows how long. I checked all of the fusible links they seem fine. All wires coming off of the alt show 11.97-12.06. Same with the starter relay and battery. The funny thing... and might be unrelated... is the two wires going to my coil show anywhere from 12.85-13.30 at idle. When rpm"s are brought up they show approx. 14.5. Alt wires and all other wires as rpm is brought up don't change they stay at approx. 12 volts. Guys and poss. ladies please help me I"m about to give up on mustangs

 

REALLY..... NO ONE CAN HELP?

 

Maybe I can help. I had a similar concern on my 93 GT. I was bored at work one day and I decided to check my charging system on my car. With the car running the voltage was in the very low 13's ( can't exactly remember this was back in 2005).I thought my alternator was taking a crap on me.My car still has the original alternator on it but I never had a problem starting it to this day. Is yours starting up ok?

 

YEA UNTIL IT KILLS THE BATTERY. I,M CHARGING AT JUST 12V BUT SOMETIMES HIGH 11,S