M939 power wires

[Floridianson]

I just got the 925 and was going to do the battery relocate thing. I have removed the battery box and stuff to redo the floor and deal with a little rust that was there because of the rubber mat. Ok can anyone help me with this problem. I know that wire # 569 is 12volt pos. but here is what I have in the pic. The heavy wire that does not have a tag and has been spliced with the white wire was on the Neg side of the 24 volts. Was this correct. Then I have the outher two smaller wires. The large starter Neg has a smaller wire in it's harness and marked Gnd A and this was on the 24 neg. side and that seems to me to be correct. Then the Pos 24volt large starter wire has a smaller wire in it's harness with the tag that has 6 B tag and that was hooked to 24volt pos. That would seem to be correct. What wire is the 569? it would seem that my white splice wire should have been the 569 but like I said it was on a ground. Everything seemed to work ok on the truck but I just want too get it right as there have been many messed up thing happen to these MV's before we get them. Thanks.

 

[Floridianson]

Ok I did find this thanks to the TM's but from what I see the 569 wire is on the Neg. On my battery box there is a sticker that says 569 is pos 12 volt. Thats what is throwing me off. Guess the sticker is wrong.

 

[goldneagle]

Ok I did find this thanks to the TM's but from what I see the 569 wire is on the Neg. On my battery box there is a sticker that says 569 is pos 12 volt. Thats what is throwing me off. Guess the sticker is wrong.

I know on my trucks one of the small wires goes to the 12 Positive terminal of the battery. There is another small wire that goes to the 24 volt positive terminal. I do not remember seeing a 3rd small wire in any of my M939 trucks.

 

[plode]

Now I'm going to have to go check my wiring to ensure it's right. My blower motor doesn't run on low, and I believe the wire that is supposed to go to 12v positive is for the low speed setting for the blower. I think the military had mine grounded...and I put it back exactly how they had it wired. And that would explain why my blower doesn't run on low speed, only high. Picture below is how mine came from the military. As you can see, both of the separate smaller wires coming up from the floor are grounded. I don't know why, but they had a 12v solar pulsetech charger hooked up to it, which doesn't even work. I've since removed that. This picture is looking at it from the drivers side.


I also just looked at the P2P software. Their picture of the batteries is showing 3 wires coming up from the floor. But the wiring diagram only shows you the 569a which is for the 12v for the blower, like I suspected.
I circled the 3 in red.

 

[Floridianson]

Great I did not check the blower. If 569 needs 12 volt power then mine should have been on positive post of first battery in the first bank.
I am loosing my mind and can't keep up with all the TM's

 

[plode]

Great I did not check the blower. If 569 needs 12 volt power then mine should have been on positive post of first battery in the first bank.
I am loosing my mind and can't keep up with all the TM's

I just edited my post above. Now I'm losing my mind too. I'm usually pretty good at wiring, but now there are these mystery wires

 

[Floridianson]

Your diagram has the 6B Ste/ice lead 24 pos. and Gnd A on the nato ground. Mine is that way. The pic is not clear where the 569 hooks but looks like between the bank. Would not hooking between the two banks of 12 still give us 12 volts. It would not matter of my 569 was on the Pos of battery one or the Neg. of two there would still only be 12 volts at that point. So that would mean my stuff is correct and just hook it back that way when I relocate.

 

[goldneagle]

Your diagram has the 6B Ste/ice lead 24 pos. and Gnd A on the nato ground. Mine is that way. The pic is not clear where the 569 hooks but looks like between the bank. Would not hooking between the two banks of 12 still give us 12 volts. It would not matter of my 569 was on the Pos of battery one or the Neg. of two there would still only be 12 volts at that point. So that would mean my stuff is correct and just hook it back that way when I relocate.

Yes if you hook it up to either terminal on the jumper wire within the circuit you still get the same voltage result. They did that so you don't have too many wires on the same terminal.

 

[Floridianson]

Thanks but I am still loosing my mind and I should have seen this before I posted. My Father is rolling over in his grave. He worked for the REA and was on the panel in 1979 that put together the NEC.

 

[MtnSnow]

Ok just be cause I'm in the process of converting over to 2 batteries in my M925a2 and the wires were a mess when I purchased it (the dealer had someone with no clue working on it)...

So the as I see it since there are 3 small wires within my battery box and it "did" have the STE/ICE sensor unit in the lift pump...

"6B" (STE/ICE) small wire goes to the same positive post that has the heavy Positive cable coming up from the floor to starter as well as the positive lead from the slave plug.
"569" small wire goes to the Positive Post of the second battery or the Neg post of the battery that has the main heavy positive cable (aka the inter-tie cable location)
"Grd A" small wire goes to the Negative post of the second battery along with the slave negative cable & main engine ground cable (up from floor) (-24v spot)

 

[74M35A2]

I did not read all the responses this time, and shame on me, but basically the 12V wire goes to the + of the "first" battery, which is the battery that has the large - cable on it. This is really also the same as connecting it to the - of the second battery, which has the large + cable on it. Same-same. I just went through all of this on mine. Here is a schematic of the 12V "lo" side blower lead:

http://www.steelsoldiers.com/attachment.php?attachmentid=540352&d=1422904268

 

[CARMAN]

Ok I did find this thanks to the TM's but from what I see the 569 wire is on the Neg. On my battery box there is a sticker that says 569 is pos 12 volt. Thats what is throwing me off. Guess the sticker is wrong.

Having the same issue. My #569 says it is 12v power on the diagram but hooked to the negative ground.

 

[CARMAN]

Charging the batteries......

One of my guys thought he would take a look at the truck and must have flipped on the battery switch, which I'm paranoid to cut off every time. It is 100% dead with 3 new batteries. I've never had to charge or jump a 24v system so I don't want to screw anything up. It's a 923a1 with the 250...

www.steelsoldiers.com

 

[simp5782]

Having the same issue. My #569 says it is 12v power on the diagram but hooked to the negative ground.

569 Is the blower motor low speed. Should be 3 small wires with the large battery leads one ground one 12v one 24v

 

[CARMAN]

Yes. There are three. #569 that was on a negative post. Then another wire that was on the same negative terminal the truck is on. And another wire that was on the positive terminal the truck is on. All replace in the same spot with exception of the #569. Will need to move that from the negative terminal the truck is on to the other negative terminal. Here was the original set up. The small red ands black wires running on top are the solar charger wires military installed.