M923 Secret switch install

[Hoefler]

OK-have installed main electrical cut offs on my A3 and past Duece. Just installed in the ground curcuit from battery to buss bar.
Now trying to do it on the 5-ton and am baffled. After taking off several battery cables and hitting the start-this gal starts right up. I have a schematic that shows I could fix in the positive cables-dont want to do that.
Has anybody done this and how the heck did you get it done.
Have tried and about the only thing have found-my truck must have another secret stash of batteries that enable it to run with the under seat group dis abled!
Pete

 

[goldneagle]

OK-have installed main electrical cut offs on my A3 and past Duece. Just installed in the ground curcuit from battery to buss bar.
Now trying to do it on the 5-ton and am baffled. After taking off several battery cables and hitting the start-this gal starts right up. I have a schematic that shows I could fix in the positive cables-dont want to do that.
Has anybody done this and how the heck did you get it done.
Have tried and about the only thing have found-my truck must have another secret stash of batteries that enable it to run with the under seat group dis abled!
Pete

I just did it to my M923. You run the ground from the NATO receptacle and the ground to the frame together to bolt #1 on the switch. You run a cable from the Negative battery terminal to the #2 bolt on the switch. (I think the ground on the NATO receptacle is grounded to the body)

 

[jcappeljr]

I just put a master cut off on my 932a2.Put it on the ground cable going to the frame.

 

[nf6x]

I just did it to my M923. You run the ground from the NATO receptacle and the ground to the frame together to bolt #1 on the switch. You run a cable from the Negative battery terminal to the #2 bolt on the switch. (I think the ground on the NATO receptacle is grounded to the body)

That is correct. The slave cable probably won't provide a good, reliable connection to ground since it is bolted to thin, painted cab sheet metal, but it can't be relied on to be isolated from ground, either.

Like goldeneagle says, it is necessary to interrupt both the frame ground cable and the slave connector ground cable with the cutoff switch.

Here is how I installed a battery switch in my M923:

http://www.nf6x.net/2012/04/m923-gets-a-keyed-battery-switch/

Now I need to grab a jacket and a flashlight so I can go double-check that I wired it right...

 

[Hoefler]

Thank you for this information.
Pete

 

[MyothersanM1]

I had installed a battery/ground cut-out switch shortly after obtaining my truck. I later installed an M939 Battery Box Upgrade kit which included converting to a NATO style slave receptacle. I installed the NATO plug per the kit spec. sheet. The neg. cable from the plug bolts up to neg. bus bar (insulated from the box) in the battery box. Well, the NATO plug's neg. lug, by construction and attachment is not isolated, causes a reverse ground to the frame via the battery box and its mounting brackets. This rendered the cut-out switch useless as there was still continuity back to the batteries. I ended up attaching the NATO plug's neg. cable directly to the frame ground. Problem solved.

 

[Carlo]

That is correct. The slave cable probably won't provide a good, reliable connection to ground since it is bolted to thin, painted cab sheet metal, but it can't be relied on to be isolated from ground, either.

Like goldeneagle says, it is necessary to interrupt both the frame ground cable and the slave connector ground cable with the cutoff switch.

Here is how I installed a battery switch in my M923:

http://www.nf6x.net/2012/04/m923-gets-a-keyed-battery-switch/

Now I need to grab a jacket and a flashlight so I can go double-check that I wired it right...

Thats a nice step by step instalation.