Charging System Help

[KitRacer]

Okay, I dont like asking dumb questions, but I cant figure this one out and it has been troubling me for 3 weeks now.

Vehicle: 1994 Chevy K1500 4x4 5.7L Automatic

Problem:
Driving home one night my alternator light comes on and the volts drop to 11 or something. I put a new alternator in and everything seemed to be alright. 2 weeks later, i get the same thing. This time when it happens i unhook the negative. Even with the negative unhooked and the charge light on and the volts dropped, the truck stays running. Also, the light will come on and the volts will stay up, or vice versa. The alternator has an internal regulator with one exciter wire. The wire goes out of the alternator, through the light and into the ignition fuse. When I run a jumper wire to the exciter wire the light goes off weather the volts is at 14 or at 11. This is an intermitant thing most of the time it is bad at start up and after 15 minutes the volts goes up and the light goes off and then things become intermitant. When the volts drop the lights get dim so i know its not a bad gauge. RPM's seem to effect it, i can make the light go on when i rev it up sometimes. I checked all connections as well. Battery is a brand new optima and the alternator is a rebuilt autolite. The only thing that is questionable on the truck is the hokey alarm install by circuit city, so i unplugged it all and used the jumper to excite the alternator w/o needing the ignition input and that still didnt work. Thanx for the input, i really dont want to take it to the dealer.

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[Ryno]

Funny, mine did the same thing a LONG time ago. My problem was a wire got knicked when I was putting on the headers, and only at certain times would arc over one the manifold bolts. Check the coil for burn marks as well. That happened to me too, same thing, dependent on RPM's. Only other thing that comes to mind is a bad regulator/ alternator, I've never seen a bad one that's that new. The bearings usually go first. Good Luck!

Ryan

[91yotaprerunner]

take it to kragen and have them run a test on it, my toyota did the same thing, i replaced the alternator and battery, what happened was when i first started having problems we thought it was the alternator, so i replaced the alternator, all to find out it was a dead cell in the battery, after that i replaced the battery and i had problems two weeks later. While the old battery was still on it fried the diode trio in the alternator. The diode trio helps regulate the alternator, this problem occurs mostly with GM vehicles, if it goes bad the alternator will test that it is good on the machines, but it is actually bad. The electrical test at kragen test it on ur vehicle and checks the diode trio also. And it is possible to get a faulty alternator also, i know a few people that have had that problem.
hope that helps some