Manager Forum

I have a 2001 chevy impala with a 3.4L. Customer stated that the battery light came on so they replaced the alternator. That one quit working right away, so they got another alternator. That one got extremely hot after 10 minutes of running. That one does bench test bad.

I get the car and clear the codes, had a p0560, p0620, I am going to install a ac delco alternator as the others were just aftermarket alternators. I tested the wiring from the pcm to the alternator and it ohm tests good; red wire at alt and pin 61 conn 2 of pcm. The orange wire at alt has power on it, as does the big red wire. Is there a possibility of it having a bad pcm causing it to trash the alternators? The customer did not have the codes cleared after installing either of the other 2 alt. I will be clearing it codes after I install the delco alt tomorrow.

Any help appreciated.

you may have a bad alternator however there may be other issues here. without the voltage reading i can't say why the second alternator overheated and burned up. to answer your question about the pcm causing an overcharging issue in a round about way it's yes. it has to feed through the bcm. i've gotten into the habit of looking closely at the battery lugs and cable ends. to many times they've been corroded enough to cause an alternator overload. if the primary feed wire to the alternator is corroded at the lug then the alternator is charging but isn't feeding the battery causing it to basically overheat.

WELL CHOCK ONE UP TO STARTING AT THE BEGINING. AFTER ALL THAT THE CUSTOMER HAD DONE THEMSELVES AND I FINALLY GET THE CAR. MINUS AN ALTERNATOR, SO I GET AN AC DELCO. STARTED THE CAR AND THE MAIN BATTERY WIRE TO THE ALTERNATOR WITH THE CAR RUNNING HAD ONLY 4.8V ON IT!!! SO I DID SOME BACKTRACKING AND FOUND THE MAIN TERMINAL ON THE STARTER WAS LOOSE. TIGHTENED AND WA LA CUSTOMER IS HAPPY. SHE WAS TOLD BEFORE IT CAME TO ME THAT IT WAS THE COMPUTER DOING THIS ALL ALONG. I AM GOING TO GET SOME GOOD WORD OF MOUTH ADVERTISING AFTER FINDING THAT, ANOTHER SHOP DIDN'T!!! ATTENTION TO DETAIL IS WHAT IS SAY. THANKS FOR THE INPUT. I SON'T KNOW HOW TO PUT FIXED ON THE HEADING, BUT CAR WORKS.

great work. i see to many issues like that in my shop as well.