Battery light is on. Draining my batteries. I've changed both batteries, the alternator, glow plug relay. I've narrowed it down to the power wire going from the hot side of my starter solenoid toward the fuse box. But I have pulled every fuse and relay in both the outside and inside fuse box and it continues to show a dead short between the negative post and terminal on my battery when hot is hooked up and I unhook the negative side and put my meter across from the post to the terminal. 12.8 volts or so.

 

Welcome to FTE.

Which Engine do you have? What year is your truck? Are the batteries a matching pair? Where did the Alternator come from?

 

I think it should be showing 12 volts across the gap with the battery unhooked. That may not be an indication of what you are really looking for. Hard to say. Its shows that the truck would use some power if you hooked the battery up, but a potential to take 100 amps or 0.1 amps looks the same in that situation.

So you might still just have a small drain somewhere, but if the battery light is on, that might be an indication instead that the alternator is not coming on. You be the judge of that. I like to take voltage readings with the engine off and then running and go by that.

 

Its a 2001 with 7.3 liter diesel. I completely disconnected the alternator with truck off. Doors closed. Hood light disconnected. Still shows a dead short. Batteries are matching, brand new. Rated for truck. Alternator is from Oriellys.