Master shut off not a master

[Carolina1010]

I put in the iceco yesterday and discovered something weird.......
The master battery shut off is not a master at all.......when on I have 24 volts to the rear power plugs (4 of them)
But when the master is turned off I still have 12 volts to the plugs
Outside of the obvious, is there anything I need to worry about
The iceco is auto detecting for voltage so I think I'm ok there, just wondering if I need to 86 the project till I figure the wiring out for rear plugs....

Is it as simple as just adding a second master kill switch on the second leg of 12 volt, or am I looking at some weird ass electrical snafu thats going to take brains to fix?

 

[chevymike]

Master battery shut off??? I have not seen that in any M1010 before.

 

[Carolina1010]

It was added after the fact, I think when the police dept had it...

 

[Barrman]

You are in experimental land with this one. Keep in mind that no power is actually pulled from the front battery. The 12 volts positive for most of the truck systems is actually pulled from the negative side of the rear battery. Kind of confusing to think about and even tougher to disconnect/reconnect with a single switch. Removing that switch might be a good idea.

 

[chevymike]

Yeah, who knows what they did. You need to figure out what that switch is triggering. My guess is they didn't understand how the CUCV's are wired and it is likely back feeding from the front battery which is the one that supplies 12v to all of those systems.

 

[Keith_J]

Watch the sign on your digital volt meter. It is possible to wire a 12 volt cigarette lighter receptacle to the back battery using 12 volts negative and 24 volts positive. This makes the negative 12 volts above ground. Works fine but can cause digital meter confusion. That negative sign is often overlooked. Old school needle meter would see it peg negative, digital are happy with just a negative symbol.