Mystery power failure

[dhaumann69166]

Hi guys hoping maybe this has happened to someone else and they know what my problem is. A while back I went to start my Humvee and had no power when I turned the key on. Checked and cleaned connections and grounds everywhere I could think of and got nowhere. Just out of curiosity I ran a wire from battery positive post to the run position on my key. Turned it on and glow plugs cycled, engine cranked and fired up and everything worked fine. I can disconnect that wire while it’s running and it stays running fine, charging fine, all gauges and lights are good but once you shut it off it’s back to no power.
I don’t really want to keep running it with this jumper wire but due to tranny issues in my dodge I need my HMMWV running good and reliable. Any help would be greatly appreciated!

 

[NDT]

Key? Do you have a key?

 

[Action]

It could be anything from...
the punisher grill,
the wipers parked on wrong side,
the car phone antennae between the windshields,
a keyed start switch ?????

If you have an antennae on the outside, that must mean there is something electronic you added to the inside?

 

[Coug]

So what you are saying is that you aren't getting 24V to the start switch (and if it's a key switch you should ditch it and put the original paddle switch in, as a lot of key switches have been known to cause issues and kill start boxes)

If you haven't already, download TM 9-2320-280-20-1 and go to page 2-42. That is the start of the diagnostic flowchart for startability issues.
It will immediately send you to page 2-261 Starter Circuit.

Then just follow the diagnostic flowchart.

Here are what the first 2 pages of that section look like:

 

[papakb]

It helps us to help you if you tell us what your driving, or trying to drive!

Both of these circuits pass thru the control box. The signal path is like this:

Battery (+)
Control box engine connector pin E
Control box body connector pin G
Run/Start switch in
Run/Start switch START
Neutral start switch
Control box body connector pin A (Early 998's have a start lockout circuit that prevents trying to restart a running engine, removed in later control boxes)
Control box engine connector pin I
Starter solenoid


Or you forgot to put it in neutral..............................

 

[Coug]

Hi guys hoping maybe this has happened to someone else and they know what my problem is. A while back I went to start my Humvee and had no power when I turned the key on. Checked and cleaned connections and grounds everywhere I could think of and got nowhere. Just out of curiosity I ran a wire from battery positive post to the run position on my key. Turned it on and glow plugs cycled, engine cranked and fired up and everything worked fine. I can disconnect that wire while it’s running and it stays running fine, charging fine, all gauges and lights are good but once you shut it off it’s back to no power.
I don’t really want to keep running it with this jumper wire but due to tranny issues in my dodge I need my HMMWV running good and reliable. Any help would be greatly appreciated!

So you're running a jumper wire from the batter to the "run" position on the key switch, not the "Battery" or power inlet portion of the switch?
If I'm reading things right, wire 11A should be the power into the switch. That is the wire spot you should be putting power to from the battery for your hotwiring. If it doesn't work at that spot, then it's a bad switch, plain and simple.

If you are hotwiring at 11A then it's either wiring issue or your control box is shot.

And since you mentioned "key" and not switch, the use of aftermarket key switches have been known to cause electrical issues, including killing the control box.

 

[frank8003]

Oh, it was run thru water that got in connections
maybe it will dry out

 

[Milcommoguy]

You guy's have taken all good guesses. LOL

I'am out, CAMO

 

[osteo16]

Keyed ignition contacts are carboned over because they cant handle the current.. Ditch the keyed ignition before your ride burns down.. Just saying..