1978 Other Chevrolet Models charging problem

TIM77375

MEMBER
1978 CHEVROLET
V8
2WD
AUTOMATIC
15,000 MILES

My battery was 7 yr old and stopped charging, I bought an Optima battery and I noticed the amp meter was - 8 so I took the alternator to the auto shop and they confirmed it was not charging, I replaced it along with the belt. I drove home and the truck died. I put the battery on a charger over night. I took the truck to advance auto and they hooked up a meter to the battery and said the alternator was not charging the battery. I replaced the alternator 3 times and it still wont charge the battery. When I drove the truck home from advance auto my radio stopped working, dash lights went out, head lights went dimm. I noticed the amp meter was now -15 and I made it home and recharged the battery. Alternator is a one wire, same model number that was replaced, I cleaned the connectors to the battery. I turned on the headlight with the key off and the lights are bright. Any thoughts on what else to check?

1 Reply

HMAC300

MECHANIC
48,601 POSTS

Check your wires leading to the starter from the truck itself. You may have a fusible lilnk burnt up, they are smaller wires connected to larger wires they are there to stop the truck from getting burnt up. Also trace your alternator wire back and see if it is touching metal somepplace as it may have burnt through. It may lead to the starter as well and is shorting out someplace. You may also have a draw on the battery after shutdown. Put a test light between the cable and battery with the truck off and see if it lights. If it does you have a draw. Pull fuses one at a time until the light goes out and that's your area to check. Also the auto parts tore may have a run on bad alternators as well.