M1088 with 4 (Four) leads into the battery box

[Mullaney]

I have had several postings about this. Today I am as close as I have been yet, but still not functional. Picture is attached that I used to make my battery connections.



I have FOUR WIRES into the battery box. I metered all of them and two come back as ground. IE: I had one end of the continuity meter on the frame, the other on a battery cable lug (connector). Two make the meter emit a tone (completed circuit) two do not.

The SHORTEST cable into the box (back left corner) measures to be a ground.
Next shortest I can only guess to be the 24v positive connection

Picture of the box with nothing in it is below.



For whatever it is worth, I am ignoting the NATO Slave Cable connections laying off to the right of the box.

Connected everything according to the yellow picture above and turning on the green "master power" switch on the dash causes the fans on the cooler beside the spare tire to turn on (normal). I also here a series of relays that click (also normal). Pressing the started button results in NOTHING. No click, no attempt to engage.

Headlights turn on if that matters.

I am at a loss. Wondering if maybe both of the "negative" cables need to go to the same post? Anyone with ideas or suggestions? I really don't want to let the smoke out of my truck if I can help it...

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[Ronmar]

Both negative terminals?
There is one negative cable(not including the nato cable) and it goes to the shunt under the air filter/AOP then to the starter. The main chassis strap goes from starter ground line to left frame rail.
there is one 12v cable, it goes to the polarity protection device inboard from the spare tire.
there are two 24v cables. One goes to the polarity protection device and the other goes to the starter...

 

[NDT]

The super short one at the left rear is not a ground!!! It is +24. if you put the batteries in there per the graphic, there is no way it will reach a ground post.

 

[Mullaney]

The super short one at the left rear is not a ground!!! It is +24. if you put the batteries in there per the graphic, there is no way it will reach a ground post.

Agreed and that is one of my big concerns. Continuity meter reads that cable as going to ground. And yes, It won't reach any post other than the far back left (positive battery terminal).

Maybe "the stupids" were attacking me this morning and I should go meter it again...

 

[Mullaney]

Both negative terminals?
There is one negative cable(not including the nato cable) and it goes to the shunt under the air filter/AOP then to the starter. The main chassis strap goes from starter ground line to left frame rail.
there is one 12v cable, it goes to the polarity protection device inboard from the spare tire.
there are two 24v cables. One goes to the polarity protection device and the other goes to the starter...

There are 6 wires into my battery box. All appear to be "factory" or at least made at the same time in the same place. NATO is two (I am ignoring those for the moment)

I definitely have the 4 wires that you see in the picture. I swear. I'm not making it up... I am just guessing two positive and two negative.

 

[Mario]

There are 6 wires into my battery box. All appear to be "factory" or at least made at the same time in the same place. NATO is two (I am ignoring those for the moment)

I definitely have the 4 wires that you see in the picture. I swear. I'm not making it up... I am just guessing two positive and two negative.

Yes.
2 are 24V. I imagine that one for the starter and the other one into the cab.
1 is 12v
1 is gound.

 

[Mullaney]

Yes.
2 are 24V. I imagine that one for the starter and the other one into the cab.
1 is 12v
1 is gound.

Sounds like the best plan is to quit standing and start crawling - under the truck that is... Silly as it sounds, I believe that is the only real answer to the problem that I have. I just don't quite have the "umph" left in me today to crawl under that thing. Hopefully tomorrow will be the day.

Thanks Mario I appreciate the advise!

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[JD4044M]

Yes 4 wires just put 4 new ones in my truck. 2 are for the12 volt and 2 for the 24 volt. Thee long 2 are the 12 volt. I will take a new picture for you easy to see this on the new ones.

 

[chucky]

The 2 short go to back left battery positive------ next longest to right rear battery negative------- longest cable to right front battery negative . in this format all batteries have the positive lug to rear of box and neg post toward front of box meaning the drivers side out towards you

 

[JD4044M]

Got the pictures of my wiring. I put red caps on the positives. Pictures taken facing the batteries. Not sure about the 4th wire I don't see it? Count the wires it may add up to a 4th one?? You may have a heavey extra cable pos or neg.

 

[Mullaney]

Got the pictures of my wiring. I put red caps on the positives. Pictures taken facing the batteries. Not sure about the 4th wire I don't see it? Count the wires it may add up to a 4th one?? You may have a heavey extra cable pos or neg.View attachment 818999View attachment 819000View attachment 819001View attachment 819002View attachment 819003

THANK YOU!! This is great!
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[Mario]

Sounds like the best plan is to quit standing and start crawling - under the truck that is... Silly as it sounds, I believe that is the only real answer to the problem that I have. I just don't quite have the "umph" left in me today to crawl under that thing. Hopefully tomorrow will be the day.

Thanks Mario I appreciate the advise!

.

You shouldn't have to do any crawling.
As I explained last week, if you grab a lead wire (any insulated wire or even an extension cord) and a multimeter, you can get this figured out in less than 10 minutes.

Set multimeter on continuity or resistance test and go to town with it.

With all power off, the shortest cable will either go to cab's 24V distribution lug or the starter.
The other short'ish cable will be the other 24V.
If you do get bleed-thru the starter's windings, you might have to disconnect the cable from starter.
Your 3rd cable is 12V and again, it'll go to the cab's power distribution box.
The 4th and last cable is ground.

 

[Floridianson]

JD maybe I do not see it or you did something different. On mine both banks of 24 are bonded together and both POS. 12 volt are bonded together.

 

[Third From Texas]

Yes.
2 are 24V. I imagine that one for the starter and the other one into the cab.
1 is 12v
1 is gound.

That is how my 98 and 94 trucks are.

My 2008 only has one 24v in, but the other trucks had one extra 24v lead.

But *absolutely* do as Mario suggests and meter out the leads. Be a pity to fry some of the expensive bits.

 

[JD4044M]

Both my 12 volts Positives are tied together at the back of the Box nearest the frame. I do see something different from the sticker but mine does not have the sticker and they were Military installed ones. I will study the picture more and manual. I know it all works fine. Might be I am only using 1-12 volt out of the group (for 12 volts) not sure? Note# I see what they did. They were pulling one 12 volt pos and both negs for the 12 volts but only used one 12 volt battery not both. Might be why that one went bad quicker then the other 3 did being over used??? I will correct that in the wiring. Will need to crimp up a cable for it.

 

[Mullaney]

Got my battery box stuffed with 4 batteries and the wires are where they belong. Nothing smoked when I attached the wiring from the truck. One of the sweetest sounds there in the world was hitting the Main Power switch and hearing the aftercooler fans power up, then the (normal) relays clicked and clacked. When I pressed the Start Button - she fired right up!

Again, THANKS to everyone who offered information. I do really appreciate the help!

 

[spankybear]

Now go for a drive! I really love driving my LMTV!

 

[Mullaney]

Now go for a drive! I really love driving my LMTV!

View attachment 820013View attachment 820014

Absolutely!! We had to go for a spin around the block this morning. Shook off the leaves and dusted off the cobwebs! Thinking I may take her to the car wash tomorrow since it is supposed to be a little warmer. Not that the truck needs a bath, but a little high pressure water can't hurt - and the attention it will get is even more fun.

 

[Goodpedro]

Yes.
2 are 24V. I imagine that one for the starter and the other one into the cab.
1 is 12v
1 is gound.

 

[Goodpedro]

With the picture above of the 4 wires coming un the battery compartiment....can Someone specify which is the 12 v (i know super short is 24v, and clarify the training 2 please