So I've got an 82 pickup. I was having a charging problem and thought that my voltage regulator was going bad so i replaced it. After that didn't work I realized the alternator had simply come loose on the bracket so the belt was simply slipping After that all was good for a little while but then it wouldn't charge again. Went back to the store, the tester said the voltage reg still wasn't working, so i put in a new one, again. After that the truck seemed ok for a little while but then it would stop working intermitantly, sometimes for an hour sometimes for a week. being that i had no time to take out the alternator i had to charge the battery at night and hope the next day the charge light would go off for as long as it could. Finally i just put a new alternator in yesterday. Still nothing. the alternator they gave me was the same as what came out except the plugs were different. old one had a plug with 1 blade on top horizontal, 2 offset vertical blades on the bottom. its a 50 amp. the new one has 1 horizontal blade on top and 2 vertical except there in the center so the plug didn't fit. also a 50 amp. I took the plug apart and used the old plug case from the old alternator to make it fit with the new one. I suspect i could have the two top wires mixed up but i don't think so. I have yellow (alt) to yellow (truck) on the bottom, white (alt) to white with black stripe (truck) top left, and black (alt) to green with white stripe (truck) top right. Any one have any ideas?

 

Promptly retrieve your original alternator..

They gave you a 40 amp (green plug w/ green band), instead of the 55 amp (black plug w/ black band)..

The regulators are not compatible.

 

Its the 50 amp alternator trust me. It is identical to the one that came out that worked fine for over a year. The old one had an adapter on on it just like this one, except this one came with a different adapt for some reason. Ive cross referenced all part numbers with toyota and it comes up as the 50 amp. At this point what I'm really wondering is if I put the adapter together correctly. This is the wiring configuration I have now yellow (alt) to yellow (truck) on the bottom, white (alt) to white with black stripe (truck) top left, and black (alt) to green with white stripe (truck) top right

 

figured it out. it was just a bad alternator from the store. swapped it for another one and all is good

 

I had the same problem last year and beat my head against the wall for months, mostly because I'm not too good at troubleshooting anything electrical unless it is a remote with dead batteries. I also got a 55 amp voltage regulator thinking that's what was in my truck. It was only after I switched to a GM one pin setup that I realized that I had the 40 amp system. I won't go back to the stock charging system because the GM is so simple, internal regulator, and they are very common in the parts store.