The Stovebolt Site Forums The Shop Area The Electrical Bay Bad alternator?

Hey Guys -

First it what is sure to be many questions about my newly aquired truck. In case you missed it, here's my intro post:

intro post

The original ignition key must have broken at some point, because the PPO (previous previous owner) had wired up a toggle switch, with a push button start. The toggle switch turns the truck on and off, kinda. With the switch "off" pressing the start button still causes the starter to turn, but the motor won't light, I would guess no spark. And with the switch "off", the generator light lights up.

The PO (previous owner) told me the alternator was bad, but he gave me a new gm alternator to replace it. I haven't tested it yet (I will tonight) but I wonder if the it's fine, it's just that the wiring is bad, and is sucking power from the battery when it is "off". What do you guys think?

I'm planning on replacing the wiring with a "It's a Snap" or "EZ Wiring" kit, very soon.

Thanks.

Which alternator do you have, internal or external regulator? Either way, the only way it can drain the battery is for a diode to be leaking a little current, or the idiot light circuit isn't being broken with the switch off. Disconnect everything except the main charging lead on the back of the alternator, and see if the light goes out. I agree, it's probably a wiring problem. If you've got an internal-regulated alternator, you can check out the alternator by inserting a shorting clip into the D-shaped hole in the rear of the alternator, while it's running, and connecting the brush holder to ground. The alternator should go into full output. If it works that way, and not otherwise, the internal regulator is bad. Easy fix!
Jerry

Hey, Nic

I just posted a bunch of cool links about wiring your truck ... check them out Here.

Thanks Alan. I've actually read every one of your aticles at least twice, it not more. I'm ordering an "It's a snap" kit today, along with relays and fusable links. Hopefully I can get started rewiring this weekend.

I spend some more time going over the wiring last night, and I don't like it. The PO did a pretty nasty job.

Have fun wiring, Nic!

After 50 years the wiring on these old trucks can be quite shocking! Mine was UNBELIEVABLE!!! And it sure felt good, after I rewired, knowing that all was safe and secure in the electrical department.