Electrical glitch

[Dewey]

I put my new motor and trans back in the car in May. Ever since then I've been chasing the same gremlin. The alternator only seems to charge when it feels like it. I've changed it twice. The volt light on the dash wasn't working so I pulled the digital dash apart, cleaned all the connections and checked all the bulbs. Put it back together and everything seemed fine. I even took the car to BPG Columbus and it behaved itself. Got home and within a week it's doing the same thing again. I never get a voltage light on the dash but my scanmaster tells me when the system voltage is down. It's always at 13 or higher when it's charging and at 12 and less when it isn't. I can't find anything wrong with it. The grounds check out and I have continuity to the volts light. I put a tester on the 4 prongs on the back of the alternator and none of them are putting out any power so of course there isn't going to be a voltage light, yet it isn't charging. I'm stumped.

 

[BlackBandit]

If your voltage light doesn't turn on with the key on then your field won't get any power and the alternator won't work. I would guess that if you have intermittent charging then your problem probably lies there. You can unplug that wire (the little one) from the alt and check the voltage when it's not charging. If there's no problem then start there. Another thing to check are your grounds. I know you said you did but grounds can be tricky. A multimeter measures resistance but if you have a small engine/body ground that's good and one of your big grounds is bad a multimeter will make your ground look good even though it isn't. This happens allot when people paint a new engine and put it in without making sure the block is bare metal wherever a ground strap goes. Just a couple thoughts to get you going.

By the way, My friend sounded interested in that engine but I forgot to get back with him. I'll try and call him today. Good luck. james

 

[gczarny]

I had the same problem after new motor installed , check your main ground on the front cover stud , mine was loose inside the connector end , hard to spot .

 

[steve hughes]

I have seen the small brown wire on the alternator plug break internally cause this problem. Replace the plug. The wire breaks right at the plug inside.