M998 Wont turn over after hard rain

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EODDave
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M998 Wont turn over after hard rain

Post by EODDave » Thu Jun 22, 2017 4:02 am

This has happened twice now. First time I was driving my m998 in heavy rain. I parked it and came back out to it 20 mins later. It would not crank over. I had to get it towed home. A few days later it started fine and had no problems for months. A few weeks ago I changed out the glow plug controller box. I upgraded to the newest version. It works great. I drove it 30 times or so since then. Last night I tried to start and move my M998 to a different spot on the property. We had heavy rain about an hour prior and I had not driven the truck for a few days. Again, no cranking at all. I checked the TM's and could not find anything that helps. I check the continuity on the neutral start switch and its good. I'm guessing water is dripping on something in the truck causing a bad connection but I don't even know when to begin checking. Has anyone else ever had this problem or at least know what I can do to fix this?

One note. I've taken this truck though some very deep puddles in the past, turned it off, and started it right back up afterward. I don't think its the solenoid.

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Last edited by EODDave on Sat Jun 24, 2017 6:21 am, edited 1 time in total.
M998 (1988)
M35 (1969) (Sold)
Former US Army EOD
Current USAF EOD


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Re: M998 Wont turn over after hard rain

Post by JuanPrado » Thu Jun 22, 2017 6:49 am

check the shunts through the body and the connections especially on the "exposed" side.

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Re: M998 Wont turn over after hard rain

Post by desmodromic » Thu Jun 22, 2017 7:08 pm

There is supposed to be a doughnut gasket between the start box and the body at the main connection to keep water out of the box. Is it intact on your mv?
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Re: M998 Wont turn over after hard rain

Post by dilvoy » Fri Jun 23, 2017 11:51 am

When you are having the no crank problem, are you getting normal Wait Light operation?
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Re: M998 Wont turn over after hard rain

Post by Urban Camo » Fri Jun 23, 2017 5:48 pm

Your not leaving it in gear by any chance are you.
Just a thought

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Re: M998 Wont turn over after hard rain

Post by EODDave » Sat Jun 24, 2017 6:07 am

Thanks for the replies. I am not leaving it in gear. Its in neutral when I start it. I tested the neutral start switch and it checks ok. I did install the after market grounding spider cable from Kascar months ago as a precaution when I learned about M998 grounding issues and I've never had any issues with grounding before or after. I always wait for the wait light to go out before starting (27 years military and diesel owner for 29 years :)


"There is supposed to be a doughnut gasket between the start box and the body at the main connection to keep water out of the box. Is it intact on your mv?"
Maybe the above is the problem. I not exactly sure what the "start box" is. Is this the Glow Plug Controller Box or something different?

Todays News: I think it may have dried out because it starts as normal again. It still leaves the question as to what caused it to fail to crank over.
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Re: M998 Wont turn over after hard rain

Post by Urban Camo » Sat Jun 24, 2017 8:39 am

If you open the hood and look where the windshield wiper fluid bottle is you will see a large multi pin connector screwed to a connector.
Your start box / glow controller is up under the dash . They are know to get water in them .

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Re: M998 Wont turn over after hard rain

Post by Urban Camo » Sat Jun 24, 2017 8:40 am

Before you do any connecting un connecting it is a good idea to disconnect your batteries


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