M37 electrical trouble

[Mr. Crowley]

Hi Everyone, I'm a new M37 owner. I purchased a 1954 M37. Unfortunately I didn't get a good education on operation and ran the batteries dead trying to start it (didn't realize there was an ignition switch under the light switches). Being a 24v system a friend suggested we hook jumper cables from my truck and his truck simultaneously, one vehicle to each battery.
I'm not exactly at what point but immediately after, there was no current, the starter will not engage, no headlights...nothing.
Before this happened, the battery level meter and other gauges showed signs of activity when the battery disconnect was turned on, now...nothing at all. I charged the batteries overnight and the batteries seem to be fully charged and the connections are secure. The gentleman I purchased the truck from started it and drove it onto the trailer for me and it started right up like it was running ten minutes ago.
Any ideas? Any help would be appreciated...Joe

 

[ken]

I think you may have burn't up the voltage regulator. The big box near the firewall. The cable from the generator plugs into it. But first i would put a meter on the batteries. You might have ruined the secondary battery and shorted it also. But then again it might be more simple than that. Wiggle all of the battery connections. A loose or corroded connection at the batteries and or starter will give you the same problem. Let us know what you find.

 

[Mr. Crowley]

Thank you very much for taking the time to reply. I thing you're right about the voltage regulator. The batteries seem to be fine and there's just NO power to anything. Is this something that can be rebuilt or does it have to be replaced?

 

[ken]

I could be wrong, But i'm pretty sure you will have to get another one. Try taking a meter and see if your getting power to it. I don't know what one costs but it shouldn't be too hard to find one.

 

[Mr. Crowley]

I found one on OD military parts and accessories for $102.00. It's solid state so no more breakers. I'm hoping this will be the last expensive mistake I make. My next project is to figure out why the brakes are mushy. I can pump them up but the pedal will go to the floor again in about 5 seconds. Good thing I like to tinker. Thanks again for your assistance...Joe

 

[nattieleather]

The voltage regulator will not have any effect on the starter or the lights. Those will work with out the VR if the batteries are in good shape. Did you hooke the batteries up properly? The should go from chassy to the - of the first battery then the + of the first battery to the - of the second battery and then the + of the second battery to the system. So it should be Ground to -, + to -, + to system.

Now if your system starts and your not getting any reading on the voltage gauge and the batts are going dead then you might want to look at the VR. But it sounds to me like the batteries are either messed up or not wired properly.

 

[Mr. Crowley]

The batteries have been in the vehicle for about a year and the gentleman I purchased it from had it for ten years and is very knowledgeable. The truck was running fine until I got it home.
The connections are tight and I assume the batteries are okay. They are hooked up correctly. Could they have been damaged when hooked up to the two additional batteries for a jump start? The lights don't work and nothing happens when the battery isolator switch is turned on. When I say nothing, I mean NOTHING...No lights, no ignition...NOTHING...
Before I ran the batteries down this was not the case and the truck would turn over and the lights were working.
I called the man I bought it from and when I told him what I did, his first comment, as was Ken's, is that I fried the voltage regulator. Is there a way to sort this out without buying stuff I don't really need?
Is there a way to test the voltage regulator and/or batteries?

 

[T. Highway]

Why don't you pull the batteries and head to your local auto parts store and have them load tested?

 

[Mr. Crowley]

T. Highway,
I intend to do exactly that this morning. I am very grateful for all the advice I've received. The batteries will be checked first then I'll work forward from there. I'll keep everyone appraised of my progress. Thanks again...

 

[bigbee]

If I remember right, when I had a similar problem with mine, it was a breaker connection on the support BEHIND the dash panel. There may be 2 or 3 that look like simple 2 to 1 connectors, but I think one of them is a breaker that doesn't let the switch turn anything on.
BUT, if you're not getting ANY crank at all, with or without the switch turned on, check your starter connection or see if there is a hidden master cut off switch blocking the circuit.

 

[nattieleather]

If everything is hooked up right you should get crank with out the on switch on you just wont get spark which you found out. The fact that you are dead to me states that your batteries are shot. Even if you did fry the VR you still should be able to crank and even start the truck heck you can disconnect the VR and the truck will still run on the batteries. This is what makes me think you damaged the batteries somehow.

 

[G-Force]

Take a volt meter and go from the + 24 volts terminal to the - 24 volts terminal and see if you have 24 volts. If not then the batteries are bad. If you do have 24 volts then leave the - 24 meter connection on the battery and go to the back of the disconnect switch. Turn it on and check if you have 24 volts on both of the terminals on the switch. Keep following the wire to wherever it goes from the diaconnect until you lose your 24 volts. I'll bet the disconnect switch is bad. Either that or you have a bad ground.

 

[Mr. Crowley]

Well, as luck would have it (I think) the batteries are TOAST. I bought a new charger and it has a tester built in. I had one of the batteries on for 6 hours and the needle fell to the bottom like it was cool. I'll go out tomorrow and buy a couple super amazing heavy duty batteries and see what happens. Again, I thank you for all your help and advice.
Word to the wise, don't hook two batteries up to two batteries to charge or jump, haha...

 

[Mr. Crowley]

Okay, two brand new batteries installed and still NOTHING. I check the wiring the best I could and everything seems to be intact. The wires running from the batteries to the starter are enormous so I can't see how they'd fry. Are there breakers anywhere in this system? Dammit, this has me stumped...

 

[G-Force]

You have to go from termination to termination of the + wire to ground to determine where you are losing power. Not say the cables are fried. You appear to have a bad connection somewhere.

 

[bigbee]

Do you have access to a technical manual--TM9-2320-212-20? It has step by step procedures and a wiring diagram that is designed to help you keep from being stumped.

Yes, there are circuit breakers in this system. As I said before, they are on the support BEHIND the dash panel. PITA to get to, more of a PITA to check, just plain H-E-L-L to change.

And, even large cables can fry. Or break, or corrode, or come loose. You have 6 connections just on the batteries that could be part of the problem. And if you are able to crank, but not getting any fire, check your distributor or even just your sparkplugs. Check the simplest first!

 

[NDT]

Remove the "master disconnect" you are talking about, it does not belong and is likely the souce of your problems.

 

[Mr. Crowley]

IT'S ALIIIIIIIIIIIIIIIIIIIIIIIIIIIVVVVVVVVVVVVVVVVVVVVVE,
Okay, here's the scoop: I did ruin the last set of batteries. When I replaced them I had NO idea the terminals can come in different configurations. When I connected everything, something seemed a bit odd about the connections. Anyway, VERY long story short, I had the connections wrong and the strange part is the symptoms were exactly the same as when the batteries were bad. I printed a wiring diagram off the internet at 4:30am and went out armed with my schematic.
I disconnected the terminals. The good news is I only had three out of possible four wrong and the better news is that I didn't ruin anything (again).
Once the connections were fixed and I turned the isolator and ignition switches on...BOOM...we have power. The truck started right up...well almost right up but it did start and I was able to drive it a short distance. The brakes BARELY work so I didn't want to take a chance. Again, I'd like to thank those of you who took the time to assist and I truly appreciate it.

 

[G-Force]

Ok, we did our part now you have to do your part......We need PICTURES!!!!!!!!

 

[Mr. Crowley]

No problem, I'll get some up ASAP. They'll be taken in my garage but you'll get the idea...