Glow plug controller bad and not the smart box?

[Shaun387]

Is it common for the glow plug controller to go bad and the smart box still be good? I found the four page troubleshooting guide for the glow plugs. I had time to check ohms on the glow plug controller, and my multimeter didn't budge. Seems like it is definitely bad. The rest of the testing just seems like it's for continuity on the wires between the smart box and controller? Hate throwing money at just the controller if I really need to test something on the smart box? I have the black box with the yellow label....

A little more information, I can hear the relay click in the smart box when I turn to run. The wait to start light doesn't come on, or might be super dim. Takes forever to start and puts out a lot of white smoke, then clears up and runs fine. After it's warm, it starts super easy. When it is cold, and you turn to run, the voltage doesn't seem to drop, and I'm not getting any voltage at any of the glow plugs.

 

[Mogman]

WELCOME to the forum!!
The relay you hear is the run relay, the glow plugs are powered by CMOS switches (solid state) on most EESS boxes, if the temp controller tests bad it is by far the cheapest fix there could be. you have confirmed there is no power going the the actual glow plugs yes?

 

[Shaun387]

Yes, I put a multimeter between the glow plug connection and the ground and I get 0v when I switch it to run. I did test ohms on each glow plug and get around 2 on all of them.

I am testing the glow plug controller right? You put the multimeter on the controller itself, not the harness on the electrical side? As in you could test a controller out of the vehicle if you wanted to?

 

[Mogman]

I do not know what procedure you are talking about, can you link to it?

 

[Shaun387]

It looks like the 4 page pdf I had was pulled from the troubleshooting manual found here..... Untitled-2 (gear-report.com)

Page 136 is how I was testing the glow plug controller...

 

[Mogman]

Yes that is the procedure to check the controller "out of circuit"

 

[Shaun387]

Sounds like my controller is definitely bad, so I'm going to go ahead and replace that. Reading more into it, I'm going to do the aux ground harness too.

I just noticed this on gear report in regards to the glow plug controller (unfortunately, they didn't know the original author):

> ALL/MOST later and older units used a “glow plug controller” which
> was/is a temperature sensor in the upper water manifold on the right side of
> the engine. Its’ problem(s) is that it has some electronics encapsulated
> inside it and because of the extreme temperature changes, would have a
> premature failure rate. It was a common problem and the most obvious one
> was when turning the switch to “ON”, the “WAIT” light would NOT come on
> along with the glow plugs as well. You can take a new one and plug the
> harness into it (without removing the old one just to check) and see if the
> problem is corrected. Easy fix too.

 

[Milcommoguy]

Is it common for the glow plug controller to go bad and the smart box still be good? I found the four page troubleshooting guide for the glow plugs. I had time to check ohms on the glow plug controller, and my multimeter didn't budge. Seems like it is definitely bad. The rest of the testing just seems like it's for continuity on the wires between the smart box and controller? Hate throwing money at just the controller if I really need to test something on the smart box? I have the black box with the yellow label....

A little more information, I can hear the relay click in the smart box when I turn to run. The wait to start light doesn't come on, or might be super dim. Takes forever to start and puts out a lot of white smoke, then clears up and runs fine. After it's warm, it starts super easy. When it is cold, and you turn to run, the voltage doesn't seem to drop, and I'm not getting any voltage at any of the glow plugs.

AT this point everything points to a bad controller IMO. Check the resistance of each individual glow plug. VERY low resistance in the tight range of 2 to 5 ohms more or less an ohm or two. Likely all are shot (open) but one could have gotten lucky. If open one gets the fun to change / replace them all for starters. The click / clunk is the solenoid and depending on the manufacture is normal. Still has to play right with the other 80 plus parts and a micro-controller. (in a HMMWV??? YEP)

Next the decision to go OEM replacement with fingers crossed or go manual control from Camoteksystems. One has a choice to start a dumb HMMWV without a smart ?? computer... with our product with NO more headaches in this department ever again.

Get ready boy's winter is right around the corner. This story will be front page on all the sites... "Worked great all summer... now hard starting and smoking like a train till warms up or it may never starts." (fail to glow at 70 degrees or below... coughing, ruff start, white smoke, burping, farting till warm, if it starts)

There are some other test... Most important as winter approaches are STRONG batteries that can deliver the current to glow and start.

Been there... done that. never again, CAMO @ Camoteksystems.com Owner and only manufacture of manual controllers for sale to the HMMWV hobbyist.

 

[Milcommoguy]

Yes, I put a multimeter between the glow plug connection and the ground and I get 0v when I switch it to run. I did test ohms on each glow plug and get around 2 on all of them.

I am testing the glow plug controller right? You put the multimeter on the controller itself, not the harness on the electrical side? As in you could test a controller out of the vehicle if you wanted to?

Add note... There is not not a much info on testing the Smart / Dumb controller or TSU's. What I think you will find are procedures for older GPC (glow plug controller) and simple transistor / timer logic controller. Typically LAU, Prestolite, and SSI. The companies that starts with "N" or a "K" are not sharing in the test and repair department. Depot solution... remove and replace all of it.

It's the government way, CAMO

 

[Shaun387]

Well, it was the smart box. Looks like water took it out. Going to gut it and keep it simple with a push button for the glow plugs. Where can you find a quality 24v 200a continuous duty solenoid? Reviews on Amazon are hit and miss.....

 

[Retiredwarhorses]

S3 boxes will light the wait lite even when all glow plugs are toast….only sure way to know is to test all your plugs.