Battery isn't charging Alternator?

[Hypnotic818]

Hey everyone. New here. Been searching these forums since I got my truck for helpful tips and finally decide to register lol. But I got a problem that me and dad ran into.

My problem is my Alternator isn't charging the battery. I've had the Alt tested and it was good. The battery also tested good. But when I try to start the truck it just won't turn over like a dead battery. So I jump start or push start it and it'll stay running but once we disconnect either Pos or Neg on the battery the truck dies. So the truck is running off the battery but the battery doesn't stay charged and the Alt doesn't even try to charge it. Does anyone have any ideas what could be going wrong? Wires? Voltage Regulator? Any help would be grateful.

[xsdg]

If the vehicle dies when the battery is disconnected, then there's something wrong with the alternator or the alternator wiring. Period.

As for what it could be, I don't know. There are lots of fusible links, so a good starting point would be to check continuity across all of those. Another thing to try is to check the voltage between the alternator output and ground. You should see around 14 volts. If you run this test, be careful of the belt, and be careful of shorting things out. Ideally, have someone sitting in the driver seat who can kill the engine quickly if anything goes wrong.

Also, maybe check the resistance between the alternator body and the battery ground? It's possible that you'd end up with high resistance (and thus more voltage drop) if the alternator's dedicated ground wire is missing or damaged.