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okay, that does answer my question.I am not sure why you are asking but there is a 12V feed to the TCM that is hot all the time and a switched feed.
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okay, that does answer my question.I am not sure why you are asking but there is a 12V feed to the TCM that is hot all the time and a switched feed.
It shuts down the TCM (aftermarket US Shift) which does throw it in limp mode.throwing the switch doesn't shut down the truck, but does it have any effect on the transmission control module? Do you get stuck in limp mode or does it still work properly?
Fortunately generators, unlike alternators, can run with no battery connected (or completely dead batteries) and not have issues. Alternators will burn up if you do that.It shuts down the TCM (aftermarket US Shift) which does throw it in limp mode.
I thought throwing the disconnect would shut off the fuel solenoid and thereby shut down the engine. But the generator must keep the solenoid alive.
The connection to the 14v tap off the regulator can and will also act as a ground when the ground is disconnected allowing the truck to be cranked over but on 12v only, I pointed this out years ago and stopped installing BCO’s on 200 amp equpiped trucks.Am I missing something about how these trucks electrical system work?
It was my understanding that the 12V to the TCM was operated by a relay powered by the 24V system.
With the 24V system disconnected, wouldn't that also mean that the 12V system can't be operated either?
Or does the 12V circuit go to both the relay and the TCM directly at the same time?
Steven I think that's true if you only disconnect the low battery ground. If you disconnect BOTH high and low battery ground it all goes dead.The connection to the 14v tap off the regulator can and will also act as a ground when the ground is disconnected allowing the truck to be cranked over but on 12v only, I pointed this out years ago and stopped installing BCO’s on 200 amp equpiped trucks.
Ive duplicated the issue in front of many hmmwv owners and even other hmmwv shop owners while they were in my shop.
The OEM kit eliminates the problem.
Correct, but without going into the differences of BCO on pos or negative, AM General kills the rear battery ground and the 14v positive feed, it ultimately does the same the same thing just a different approachSteven I think that's true if you only disconnect the low battery ground. If you disconnect BOTH high and low battery ground it all goes dead.
I can say that was true for me when the battery interconnect was still connected, ie cable between high and low battery. As soon as I added that to the disconnect switch everything was dead.......gauges, lights, starter, everything.
You are a gagillion times more experienced then a me on this so I may not be understanding.
But by disconnecting BOTH grounds from BOTH batteries I don't see how there can be a circuit completed of any kind. Even if the electrons leave the positive poles (I know its the opposite in reality but just to follow easier think of it like this) they have no way to get back tot he battery if neither ground has any connection to the battery. I imagine it as completely removing the ground cables from both batteries. Have to think it's impossible at that point.
Steven you may have still had the interbattery cable hooked up in which case that's exactly what was happening with me, ie 12V to many systems, ie dim lights, slow gauges, slow starter. When I put the interbattery cable on disconnect everything went dead.
Got it. That makes sense.Correct, but without going into the differences of BCO on pos or negative, AM General kills the rear battery ground and the 14v positive feed, it ultimately does the same the same thing just a different approach
I’m in the process of setting up a dual disconnect for my M1123 and was planning to copy your setup.The advantage to using a ground side switch for the 24V is if any of the cable or connections accidentally finds ground it will not start a huge fireworks display.
If you use a dual switch, one on the ground side of the low side battery and one disconnecting the 12V connection between the batteries there will be no current flow anywhere, basically doing the same job as using the 24V (high current) switch between the batteries or on the positive side of the high side battery, makes no difference only breaking the low side battery ground is as I said safer.
That may not be the right one, This one is the one I use, it is rated for 250A continious serviceSo I figure this was easier than trying to describe it.
Big switch is labeled in red.
Little switch is one of those colors?
I haven’t traced those wires, but yellow is labeled 290, 291, 537.
I was planning on running the 2500a Hella (metal) and a 1000a Hella (red plastic), is that enough switch for this role?
Battery Switches | Hella Marine
A complete range of battery switches to suit a variety of applications and power loadswww.hellamarine.com
View attachment 905842100 Amp Battery Master Switch - Accessories, Battery Switches - Hella Marine
Heavy duty switch for high loads.Key can be removed in the OFF position, current interrupted. Positive or negative cable can be switched as required. Note: Not suitable for areas exposed to water or moisture.www.hellamarine.com
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