Does Anyone Have the Diagram for Dual battery WITH the Disconnect

[Third From Texas]

Years ago, someone made several of these diagrams for the various 2 and 4 battery set ups.

I'm printing some materials to keep in the truck and I want to print the dual battery with the disconnect, but I'm missing that one.

I'm not particular of the format or color (doodle on a bar napkin will do).

 

[GeneralDisorder]

Is your cover missing the metal data plate?

 

[hike]

For the 2 battery diagram using the one above: DELETE BT2 and BT4 with their connections to BT1 and BT3; then REATTACH BT4+ to Disc12v at BT3+ to Disc12v

 

[Third From Texas]

Is your cover missing the metal data plate?

No, it's there. But it's been incorrect since I did the dual battery delete five years ago. I want to keep it documented on-board. More for the benefit of someone ever having to look at the layout in a repair shop, etc.

But in looking at it today, something just seems off when I was testing the connections at the disconnect/relay and I wanted to compare what I've got to the "dual-bat w disconnect" drawing (that I apparently deleted off my storage drive).

What started this is the disconnect switch on the driver kick panel is no longer shutting off some of my 12v stuff in the cab (that has always gone dead once the switch was toggled). Now they are getting power with the inside switch "off". The inside switch does kill the ignition (and I can hear the relay trip back at the batteries).. But I cam out the other morning and my two dash fans were running for two days (when the kick panel switch had always shut them down). So now I get to replace yet another 6TL

I started tracing from the batteries and didn't get very far. The four posts at the relay were giving me odd readings (or at least not what I was expecting to see in the off/on modes). And I'm pretty sure I was half delirious from heat stroke. But I'm wondering it it's been wired wrong all along now.

 

[GeneralDisorder]

Your disconnect relay or it's interconnecting wirings is probably shot. It's actually TWO relays in one unit - one for 12 and one for 24. And they are "latching" relays so when they change state they stay that way without power applied. Sounds like your 12v relay or the control wires to it have dropped a deuce in their trou.

See PS magazine April '22 for the deets:

M1078A1 FMTV: Culprit for Cab Power Loss

Dear Editor, my unit has had some issues with our M1078A1 FMTVs losing all cab power. The culprit is the battery disconnect relay assembly going bad. Here's a quick and easy fix...

www.psmagazine.army.mil

Mine suffered the TX failure also. One of the ring terminals that disappears into the potted mystery box hanging off the side seems to have lost it's solder joint to the board under the potting compound and after that it never worked again. Fortunately it was in the ON state and I only found the failure by tracing down why the remote disconnect switches were not working. I replaced mine with the new sealed/enclosed Bussman unit. Scary expensive and probably unnecessary but I'm a sick person so don't pick on me.

 

[Third From Texas]

Your disconnect relay or it's interconnecting wirings is probably shot. It's actually TWO relays in one unit - one for 12 and one for 24. And they are "latching" relays so when they change state they stay that way without power applied. Sounds like your 12v relay or the control wires to it have dropped a deuce in their trou.

See PS magazine April '22 for the deets:

M1078A1 FMTV: Culprit for Cab Power Loss

Dear Editor, my unit has had some issues with our M1078A1 FMTVs losing all cab power. The culprit is the battery disconnect relay assembly going bad. Here's a quick and easy fix...

www.psmagazine.army.mil

Mine suffered the TX failure also. One of the ring terminals that disappears into the potted mystery box hanging off the side seems to have lost it's solder joint to the board under the potting compound and after that it never worked again. Fortunately it was in the ON state and I only found the failure by tracing down why the remote disconnect switches were not working. I replaced mine with the new sealed/enclosed Bussman unit. Scary expensive and probably unnecessary but I'm a sick person so don't pick on me.

Thanks for the writeup and the article.

I'll poke around with the truck over the next couple evenings.