Glow plug light quick flash then off?

[buckroseau]

I'm sure it's been discussed hundreds of times, and I did a search on the forum, but didn't find exactly what I was looking for.

Just picked up a 1985 M998 last week, 6.2L. Did a few quick checks of the basics, got brand new 6TL batteries, and wanted to take it for a spin. First 3 days glow plug light came on for approx. 10 seconds, shut off and started fairly easily. I've driven it maybe a dozen times in the last 3 days, no problems. This morning when I went to start, the glow plug light flashed for an instant and then shut off. I cycled the switch several times, did this over an over. Maybe one time it stayed on for a full second or 2. The Humvee did start, but you could tell the glow plugs were not heated up all the way, started hard.

I have a green labeled box, not sure what brand. I also have the grounding harness kit, but I have NOT put it in yet.

Suggestions?

Matt

 

[Retiredwarhorses]

Green label box does not Require a TSU in the water crossover...this box too has a rather spotty past.
i would disconnect the battery's for a few minutes and see if the box resets. But most likely it's taking a crap on you.
heres the deal on the ground harness....the trucks you are buying don't have this ground harness, I have never seen a
truck come from the military with a ground harness. While it won't hurt to install it...it's my belief that if all the grounds are clean and everything so good, then it should not be needed.
just as many folks have lost boxes with the ground harness as don't have the harness....so the jury is out on these.
so your next step is to also remove and check all your glow plugs....because if you have Grenaded GP's, that will do the same thing. But I would be on the lookout for a new EESS and TSU.

 

[TedG]

I see you installed new batteries. Make sure they are fully charged and good connections (as Steve says). Low voltage will cause this and may cause your control box to crap out.

 

[buckroseau]

I see you installed new batteries. Make sure they are fully charged and good connections (as Steve says). Low voltage will cause this and may cause your control box to crap out.

I haven't checked the voltage, but it seems to have quite a bit of jam to turn it over when starting. Connections cleaned and good.

Matt

 

[buckroseau]

Green label box does not Require a TSU in the water crossover...this box too has a rather spotty past.
i would disconnect the battery's for a few minutes and see if the box resets. But most likely it's taking a crap on you.
heres the deal on the ground harness....the trucks you are buying don't have this ground harness, I have never seen a
truck come from the military with a ground harness. While it won't hurt to install it...it's my belief that if all the grounds are clean and everything so good, then it should not be needed.
just as many folks have lost boxes with the ground harness as don't have the harness....so the jury is out on these.
so your next step is to also remove and check all your glow plugs....because if you have Grenaded GP's, that will do the same thing. But I would be on the lookout for a new EESS and TSU.

So Assuming it is the box, what are my options? Something like this?

https://www.real4wd.com/zedsuite/catalog/partdetail.aspx?partno=CR2701

 

[buckroseau]

Truck started and worked perfect when I went out for lunch today? Pic of the control box I have.

 

[TedG]

Loose connection somewhere. Disconnect batteries when checking connections or you may be buying an new box.