Suddenly no "WAIT" light, vehicle won't start

[darkchao]

Hi all, currently freezing my ass off and posting mobile. Everything on the HMMWV was working fine until I went to start it 10 mins ago. Turned to "RUN" position, "WAIT" light came on as normal, I waited for the plugs to heat, and tried to start. Got nothing. The vehicle is in Neutral, and batteries seem to be fine as the headlights/interiors come on fine.

When I attempt to put the vehicle in "RUN" position now, the "WAIT" light doesn't illuminate, and it doesn't sound like the plugs heat up either. (Although you can hear a heavy "clunk" on and off, as if it's doing something.

I am still very new to the vehicles. Any insight is greatly appreciated.

 

[dmetalmiki]

I dont know the wiring on that vehicle, but That (particular) deisel engine uses a heater timer relay as I recall. I had the same symptom on my F350 deisel . And it was the timer relay for the glowplugs. Also on mine I had an intermittant starter solonoid fault. though the clunk you hear is probably that solonoid working on yours. It also swithes on the timer relay.?

 

[dmetalmiki]

P.S. Also check all and any fuses.

 

[kdaniels]

Find your control box....lower left drivers side....check and make sure the wiring harness is tight going into the box. Next...check the voltage on BOTH batterys. They will not start under normal conditions if voltage drops below 18 volts.


SEMPER FI !!

keith

 

[darkchao]

Thanks for the information - It's helped speed this process along..

@Demetalmiki - You are correct, and I have verified that the "clanking" noise I spoke of is indeed the solenoid. Something else must have failed in the box. It's good to get some technical terms behind what I'm describing as clicks and clanks, haha.

@kdaniels - Found a very nasty surprise on the control box - the connector on the top has corroded away. It was **** to get disconnected, and it made sizzling/fizzing sound when I pulled it out with the channel locks - that alone confused and scared me, as I don't know what could have produced a sizzling noise. Both sides of the connectors are dirty. I need to get them cleaned. Any ideas on how I can go about that sufficiently? I'm also very worried about the connector itself, it.. doesn't exist anymore. I took a photo for input.



I have around ten spare control boxes. One of those "oh, that's what these things are!" moments. I grabbed one and hooked it up, my "WAIT" light is back, but this box isn't heating the plugs. I'll try it again once I figure out how to clean the connectors, but I may swap it for another box and give that a shot.

I have no way to test the voltage going to the batteries right now.

 

[doghead]

You need a state listed in your location, as the rules request.

 

[jcappeljr]

Sounds like the control box or glow plug controller.I had the same problem on my m998.

 

[darkchao]

@doghead - Thank you - missed the location box earlier.

 

[Retiredwarhorses]

first of all, that sizzling noise was becasue you did not disconnect your batteries before attempting to do electrical work...NEVER do any Work on this or Other Mil Vehicles with out disconnect the Ground at the Battery Box. No idea what Start system is in your truck...most likely have fried Glow plugs...But after your sizzling issue you very may fried you PCB "Protective control box"
Looking at that connector, you have alot of corrosion, that WILL cause issues on these trucks....if its there, its everywhere....I would clean and inspect all the Grounds.

At this Time, Pull a few Glow plugs...see if they will even come out....all you need is a 3/8 Deep socket



Read the Sticky on this forum about all of this.....

 

[papakb]

I've got to agree with Steve here, it sounds like you fried the glow plugs. He put up a great posting on the G503 site that details how the start system works in these trucks that's worth reading through here: http://g503.com/forums/viewforum.php?f=63

Military electrical systems are typically pretty simple things kept that way so the average Joe can work on them without the benefit of the college degree you need to work on todays civy vehicles. The HMMWV does have its quirks and a little knowledge will help immensely, especially of this is your first venture into them. Steve's nailed them all pretty well in the posting.

The HMMWV is notorious for an absolutely miserable ground system and if you don't have the supplemental harness installed your asking for problems. It's super simple to make and well documented on the internet. DO THIS!!

When checking the glow plugs you can use a multimeter and read the resistance on each plug but you can also learn to read the voltmeter as an indication of glow plug health. If it dips down into the yellow when you first try to start a cold truck things are working. They may not all be good but if you get that indication you probably have enough of them working to get the truck started. Avoid using starting fluids at all costs! Your asking for trouble with it. Find the real problem and correct that first.

As a last resort you can always use the USMC control box troubleshooting trick: Give it a swift kick in the pants and see if that doesn't get you going again! LOL

Kurt