Jon C. Martin

This project truck is becoming quite a project. But at least it keeps me off the streets...

The primary problem is that when the truck first starts the battery recieves no charge (I installed a dash voltage gauge). Sits at 12 volts. It stays that way until the engine is revved up, then voltage pops to 14 and stays there. Every now and then the voltage stays at 12 no matter how much the engine revs. Naturally, I don't drive it very far when that happens and all the electrics slowly start dying. That makes me sad.

I have tested the battery and it has no dead cells and it holds a charge for weeks. I have had the alternator out twice and tested once by NAPA and once by Schuck's and both times it tested "good". I fall well into the "tighten harder not smarter" category so the alternator belt is not loose. All fuzes in the engine compartment box are good.

To add to my confusion, the previous owner installed a battery isolator so he could run a second battery and I didn't ask for a wiring diagram when I bought it. I'm not saying he did a bad job, just that there are now several after-market wires running around the engine compartment and I'm not sure where they go or why. I removed the cable running from the isolator to the second battery and it made no difference.

So, I have two questions for anyone willing to accept the mission:
1. Why wouldn't a battery receive charge until the engine is revved?
2. Does anyone have a picture of the wires coming off a *stock* alternator setup and, possibly, a short description of where they're supposed to go?

Any help would be appreciated, as my wife is beginning to make snide and insulting comments about this truck.

Jon C. Martin

Wow, no love at all, must be my breath. So I'll reply to my own message. My new hypothesis is, since the dashboard lights don't appear to function, or at least none of them turn on when the starter switch is turned, the alternator excitor circuit isn't working properly.

The next step is to check if I'm getting voltage to the alternator when the ignition switch is turned, then, if necessary, trace the wires from the alternator plug-in and see what's happening under the dash (my favorite place in the whole wide world).

needsomecam

geez dude chill most of us have jobs to do, we dont live to read and solve your problems. if you post in the morning dont expect to get some help until later that night when the people who work get off. But basicallycheck to make sure your getting power out of the ALT with your meter. Then check the regulator.

abecedarian

Maybe this will help:
http://autoshop101.com/forms/h8.pdf

arizonaguy

sounds like you have a bad alternator and the diodes are bad but its only a guess, also i dont understand why you need two batteries mabe that also has somthing to do with your problem? if somone tried to wire in another battery somthing might be wrong with the way they did that. if i was you id do everything i can to restore things back to the way they where intended.

abecedarian

arizonaguy may have something valid. The battery isolater does what? ... directs the load and charge to a battery.
So, maybe if the isolater was keeping the truck from seeing which battery started the truck, it is causing the alternator to not realize a battery needs charged.

Jon C. Martin

Thanks, Abecedarian, that's excellent information. I've always hated working on automotive electrical systems so I'm making it a personal challenge to reverse-engineer this and get it working.

And needsomecam, I apologize if I came across as demanding. I know that people have to work and I really appreciate everyone's help, but I'd posted on *Sunday* morning and was somewhat surprised that I hadn't even gotten a "check your torque convertor WFK by-pass pressure release rheostat step-down switch" response in 2 days.