My 82 f100 300-6cyl won't start after sittin over night, I charged the battery, then unhooked the cables over night then it started. Had the charge system checked and it is fine! Is it a bad connection some where or the voltage regulater bad? It's driving me nuts. The battery was checked and it is also good.

 

Could be the regulator.

It may still be the alternator.
They only check for charging output, not backfeeding.
If the diodes go bad in the alternator it will charge, but it will also drain the battery when the alternator is not turning.

Do you have an ammeter or test light?

Disconnect all the cables from the battery+ stud of the fender solenoid.
Connect one side of the meter or light to the battery+ cable.
Touch each of the other wires you've disconnected and see which one lights the light or shows a substantial reading on the meter.

 

Thanx ArdWrknTrk I'll give it a shot

 

There should be a few fusible links in addition to the alternator charging lead bolted there.
Don't be surprised to find some small draw (radio, computer memory) on one or more of these.
Be sure to close the door, so you don't find the interior light load by accident.

A test light should be bright.
Or an amp reading substantial. (an amp or more)

Let us know what you find and we can trace down the short from there.

 

It's supposed to be 15 degrees here tomarrow so I'll c if I can get the testing done, I don't have a garage so I'll do my best. I have the battery charging, and the battery cables off so I'll go from there. Thank you for the support Jim. When I find something I'll let you know. Again thank you. Fred.

 

Ok ArdWrknTrk I unhooked the positive cable from the solenoid + side I hooked my light to the +cable end, I have no light from the only wire on the + wire, the solenoid has a red wire coming off the top I unplugged it and checked it it has light. So any ideas? Thank you Fred

 

"the only wire on the + wire"?
The cable coming from the battery should go to a post with multiple other wires connected to the same post.
(at least a fusible link going into the cab and the charge wire coming from the alternator)

If you touch the alternator wire does the test light light up?
If you touch the other wire does the test light illuminate brightly?
(there may be multiple wires with little rubber tabs on them, test each one)

The red wire, is it a little wire that slips on to a smaller post and has a blue stripe?

 

The red wire has a stripe it may be blue, it is faded. I tried to post a picture of it all but for some reason I can't post attachments. There is only one wire besides the positive cable from the battery. The only light I get is from the red wire/ blue stripe from the solenoid.

 

Also there is a box under the solenoid, is that the voltage regulator? It has a bunch of wires out of it

 

Okay, that is the voltage regulator.

There is one thicker wire connected to the back of your alternator.
Where does that go?

 

The red wire you are talking about is the little one on the left right? I thought that was the power wire to tell the solenoid to crank the starter... Have you replaced the solenoid? This is a pic of my current setup, I had this problem too, and my alt charge cable(red) and cab power wire(yellow) were connected in the alt harness and attached as one on the solenoid, it was a black wire with a red stripe. I separated them now obviously, wish I had a pic of the old setup. If you have a multimeter I would use it to test amp draw instead of a test light, test lights always seem kind of finnicky to me. If you only have one wire were the bat cable connects see if it has any draw. If you do, try unhooking the wires on your alternator and see if that gets rid of the draw.

 

Thanks Cole.
I don't have a 1G setup to take pictures of.

There must be some connection for the alternator to be able to charge the battery and provide power to the cab.

My next suggestion was going to be -disconnect the large charge cable from the alternator-
Does the draw go away?
What happens if you touch just the alternator post with the test light? (with the wire disconnected)

A test light can work fine in this situation.
Numbers aren't as important as showing there is good continuity.

 

For some reason I only have one wire on the positive side, I think I'm just gonna take the truck to my son, he is the service manager at a Chevy dealer, just because it is a Ford they may be able to test everything for me.i hate to go to a Chevy place but I can't figure it out. Thank you for all the help, I wish I could have figured it out on my own. But thank you for all your help.

 

Yeah, it was in the alt harness, basically the cab power was connected to the alt charge and then inside a connector had a T that went to the solenoid. I have the old harness still I can get a pic later if anybody wants to see it.

I know, I just have experience with cheap test lights my friends buy that don't work. I haven't seen a multimeter made cheaply enough to not check for draw (yet) haha

If you only have the one wire then it's like my old setup, if its drawing current then all you need to do is unhook the alternator cables and see if that gets rid of the draw. It's not too hard, you can do it man don't give up haha

 

I had the alternator off a while back to remove a broken adjustment bolt, could I have replaced a wire in the wrong place maybe? I can't remember if the problem started after that or not.