What in the wires is going on here?

[vehiclesofvictory]

Just purchased a M998 HMMWV, not new to military vehicles, but this will be our first modern-ish vehicle. These were previously owned and used, bought by the previous owner who parked them. Working on trying to get them started and having some issues.

First, I have read the owner's guide, the General TM, the Electrical TM, and the troubleshooting video and I am at a loss what I have going on.

I have civilian batteries with 750 CCA wired correctly. I have low resistance across the shunt. I have 24V to the Start Box Pins and no continuity between the light switch pin and start box pin, so according to the video I should be good to go. What I have is a solenoid and button on the dash which I thought ran a siren, but when we go to start it, the wait light is not blinking at all. I have bad ground to the screws, but when I ground the light nothing changes. I can't get the plug off to see if the bulb is bad, and I can't figure out how to get to the darn bulb. (That's problem 1)

Problem two is I have a wire marked 575A. I can't find reference to a 575 A in any of the manuals, it starts at B. Is this a ground or a hot? 575 is the start box circuit so I assume it may be related to my problem. I have the ground octupus and am installing that as I type this. I have read about a start box bypass, but this being a military tagged wire, I wouldn't think this is a bypass. Does anyone have any idea where this should go?

Thanks for the help.

 

[Mogman]

I have no idea, obviously not a mil spec install, are you saying the large wire with the ring terminal is tagged 575A?

 

[juanprado]

Need more pics of where the wires are going to?

What kind of start switch? Oe, push button, key?

That is a 60-80's ford starter solenoid.

Maybe a winch or plow set up?

 

[Mogman]

575A should be going into that plug, it carries the power to the glow plugs from the PCB/EESS box, I assume someone cut it at the plug, put a ring terminal on it, connected it to a crap relay to control the glow plugs.
You may be in for some real "fun" if that was not the only "non spec" mod done to your truck.

 

[Mogman]

575A

 

[vehiclesofvictory]

So that is the 575A. I took off the engine harness plug and sure enough I turned it over and there is the cut wire. To answer your question there was a push button switch on the dash, but the mil-spec turn switch still activated the starter. Looks like they drew power from 27F, and 57D and 71C are unplugged. Where did you get your wiring diagram from. That would be the docs I’m looking for to try and sort this all out…

If I were looking to try and use Bubbas method, does the bypass just warm the plugs enough to start then let the engine go from there? I’m assuming the ignition is still controlled through the KDS yellow box which clunks as it should under the dash. Why bypass in the first place?

 

[vehiclesofvictory]

Just wanted to follow up and thank everyone for pointing me in the right direction. It is a bypass system. There is a solenoid that bypassed the ignition control box. We replaced the solenoid and wired that solenoid to 24v. Press and hold for exactly three seconds in cold weather and we had ignition. We have since gotten both HMMWV's running. One is great the other is rough with white smoke at idle so we will start work on that one.