***********FIXED***************


I had a problem a couple of weeks ago. I was sitting idle for a while in my 97 f150 4.6L. The battery light came on and a few minutes later the battery died. I jumped it off and let it run with the cables still connected for a bit and the other truck charged the battery good enough to drive to the parts store. I was going pretty fast on the way there, keeping the rpm's high. The light that had been on for over an hour cut off all by itself. The parts place tested the battery and alternator still on the engine. They said it wasn't charging well.

I drove the truck for two more weeks and the same problem came back. It started yesterday and the light was still on. I was speeding up in first gear and when I hit 3K RPM's the light cut off. Later that day it would cut on, but just over 3K RPM's. This morning it would not start, dead battery. I took the alternator off and got it tested, it was barely pushing like 12V. I got a new alternator and I'm still having the same problem. I changed the battery and still the same problem. I tried disconnecting the battery while running as suggested by someone else and it died immediately.

Any ideas???

Thanks!

 

Sounds like either the wire to the voltage regulator is disconnected/broken or the fuse for the voltage regulator is bad. Another possible cause is the wire from the alt to the battery it may be corroded.

 

I fixed the problem. I went through every connection checking the path and all was good. When I got to the voltage regulator plug on the alternator i took it off and the path still tested good, and it was not corroded. When I reseated the plug it sunk in about another 1/4"... yeah, i didn't have it plugged up all the way.

Thanks for the help LastSplash!