Electrical glitch question.

[Twin Pinzies]

Good to hear you found the problem. Now you can have the fun of rebuilding the original to keep as a spare.
Or if you’re just going to toss it you can toss it this way. I am always entertained trying to make broken things work.

Exactly! I proceeded to totally dismantle the old switch and found that one of the two contact points was burnt looking. I cleaned up and realigned the contacts and put it all back together to keep aside as a spare. The mechanism is quite complicated with lots of tiny spring-loaded moving parts. I did learn that it is indeed serviceable though!

[Twin Pinzies]

Ok.... this sucks!
I thought that the new ignition switch solved my mysterious dying issue, but it didn't. One of my guides reported that the truck died briefly, then came back to life twice on a tour (like someone reached over and turned the key off then back on again).
The new ignition DID make an improvement. It used to do it much more often, like two or three times in just an 1/8th mile. The new switch helped but didn't totally solve the mystery.
I have replaced the battery terminals, ignition coil, voltage regulator, battery key mechanism, and ignition switch. I have also pulled the dash out and checked ALL the electrical connections at the breakers etc.
Any more ideas?

[pinzinator]

Hook up a voltmeter to the contact that feeds the ignition, use aligator clips. Go for a drive with the VOM on and in view. If the vehicle quits and you see zero voltage at the meter you know the problem is at the switch. Continue this method downstream until you get a zero when it quits, and you have isolated the problem.
A bad ground can kill the ignition, too. That creates an open circuit.
Remember, connections that appear to be connected do not always have electrical continuity.

[Twin Pinzies]

Thanks pinzinator. Here's the latest... It started right up, ran for about 30 seconds, and died. Now it won't start or even light up the dash lights at all.
Here's what I've already done: Checked the batteries and cleaned all the terminals, replaced the coil, voltage regulator, ignition switch, and battery switch, checked the ground wire on the starter, and pulled the dash out and checked all the spade connectors.
I DO know that the emergency flashers (which work even when the ignition key is turned off) don't even work when the battery switch is on.
What does this mean? Anyone? Thanks.

[StuartL]

Get your voltmeter out and trace it back to the isolation switch. Figure out at which point it doesn't work any more...

[undysworld]

replaced the coil, voltage regulator, ignition switch, and battery switch,

Without testing these parts for failure, this is what we used to call the W.A.G. (Wild Ass Guess) system of repair. Just throwing parts at it might fix it, but in this case, it sounds like it hasn't.

You mentioned that you'd "checked" the battery. Did you use a voltmeter for this, or what...?

If you've got a voltmeter, you can test the 24v positive lead to the ignition switch and test for 24v on at least one terminal. If you don't have 24v there, then check the lead from the battery +. If you do have 24v present, check to see that it switches on/off with the key. I think you can assume the switch is wired correctly since it started up.

If your voltmeter has an ohmmeter built in, you can test individual wires for continuity.

The fact that no lights are working at all suggests to me that the problem may lie with your ground. I'd use the ohmmeter and check for continuity to ground at various places, or test for an open wire somewhere.

[Twin Pinzies]

I don't mind buyIng extra parts since I am in the process of stockpiling spare parts for future repairs. So yeah, wild ass guessing is what I'm doing on purpose. Testing wires with a voltmeter is a puzzle on a Pinzgauer. Most wires are insulated and disappear into odd places. I hate auto electronics!

[Jim LaGuardia]

Ok, enough shenanegans............... Jumper the ground terminal with battery jumper cables or move it to the body side of the battery switch terminal. You must use a meter or at least a test light to verify circuits.
The ground circuit is simple, neg cable to batt switch, other switch terminal to body. Make sure all grounds have serated washers(star washers).
Power side goes from batt to starter and continues to ignition switch terminal #30
One last item, as I have posted before, the short battery jumper can go bad. I have replaced at least 4 of these in the last year on various jobs.
If you are using AGM batteries and they are more than 4 years old, you may have a battery failing under load.

[Twin Pinzies]

Umm... what do you mean by "jumper the ground terminal?" Forgive my ignorance of electronics lingo. This truck is acting as if batteries have been removed. There is no juice anywhere that I have tested with a voltmeter. Not at the starter. Not at any dash terminals either.

[BobbyD]

When my main switch died (assisted by a lot of rust) I attached my jumper cable from the negative battery terminal and connected the other end to my freshly stripped body. Looked very crude, but I was able to move the vehicle around until the new switch arrived.

Robert

[undysworld]

As Jim has not yet replied, I'll attempt to speak for him. Forgive me Jim, if I screw up here.

For a circuit to work, you not only need to supply voltage to it, but provide a return ground. With multiple devices effected, it's a clue that you might simply have one bad ground.

On the Pinz, the "return" line (the ground part of the circuits) goes through the main power disconnect switch behind the driver's seat. If this switch, or the line from there to the ground side of your batteries is bad, you would expect the multiple failures.

He's suggesting you use a jumper cable to make those connections, just in case the ground strap or the main disconnect switch are bad. Hook one lead onto the 24v negative, and the other onto the battery side of the disconnect switch. If it works, the strap is bad. If not, hook to the "truck" side of the disconnect switch. If this works, then your switch is bad.

[Twin Pinzies]

Thanks again you guys for clearing that up for me. I think that I'd sooner attempt an engine rebuild than try to troubleshoot any more electrical gremlins. Arg!!!

[Twin Pinzies]

Ok guys, so I tried the jumper cable test and this is what happened. As soon as I made any connection from either terminal of the battery switch to the negative side of the batteries, it arced/sparked BADLY, then started to literally melt my jumper cable! Still no emergency flashers or dash lights would come on.
What have I NOT eliminated through trial and error here?

[pcolette]

Maybe I'm missing something but it almost sounds like you have the positive side (+24V) of the battery connected to the shut-off switch instead of the negative side of the battery. Any chance you reversed the cables in the battery compartment?

[Jim LaGuardia]

The cable with the blue end goes to 24v neg, the black cable goes to 24v +.
If you reversed the cables to the batteries you will be replacing the diodes in the alternator