Waitlight will not go off!!!

[HMMWV Sweden]

Hi guys..today my HMMWV started acting up,when i turn on the ignition the glowplugrelay makes it's normal clunknoise and the wait light turns on..but does not go off. After about 20 seconds i started it anyway and starts up right away as usual..but the waitlight does not go off until i turn the ignition off and the same clunknoise from the relay..so relay seems fine and glowplugs work so i'm thinking what controls how long time the glowplugs are active?,is there a sensor,thermostat,bimetal strip,timer somewhere that tells the nartronbox when to turn off the glowplugs??sensor in the engineblock,inside the nartronbox??,TSU acting up??and is it repairable or do i have to order new parts??

I have searched the threads here on SteelSoldiers but haven´t found much related to this issue in previous threads,pehaps there is one and i have missed it and in that case i apologise for that.
And also posted on FB in a HMMWV group but no luck yet so...(photo of the box in my HMMWV)

So anyone here got some ideas to what could be causing this issue with the waitlight???

Thanks Anders/Sweden

 

[jkcondrey]

Most likely bad box or temp unit. Have you visually and physically checked the glow plugs and box grounding points?

 

[TOBASH]

Disconnect battery and reconnect. If still occurs, either short circuit or more likely PCB failure

 

[HMMWV Sweden]

Most likely bad box or temp unit. Have you visually and physically checked the glow plugs and box grounding points?

Thanks for your reply JKcondrey
Yeah i have been troubleshooting and looking for bad connectionpoints today,pulled the Nartonbox and had a look inside it,but can´t find anything burnt or a burnt smell..no nothing,looks like brand new inside..but then again it´s electronic stuff so there can be stuff broken that´s not visible,,haven´t measured the plugs but the engine starts just fine when cold so..no white smoke or running bad either. The Nartronbox has good ground and all instruments work just fine but it doesn´t hurt to go over some ground point for sure.

 

[HMMWV Sweden]

Disconnect battery and reconnect. If still occurs, either short circuit or more likely PCB failure

Thanks for your reply Tobash.
I´ll have another stab at this tomorrow,putting the Nartronbox back,cleaning the connectors with contact spray and see what happens,maybe i get lucky,fingers crossed.

 

[papakb]

The important thing is is the glow plug relay de-energizing after its normal 10 second heat cycle? If the light staying on is the only problem its one you can live with but if the glow plugs themselves are staying on then you have to fix that before you do more driving. You can check for voltage on one of the glow plugs to see if they are staying on without creating any additional problems. Chances are that if there is still power to the glow plugs after starting one of the MOSFETs in the Nartron box has shorted. If everything else looks good inside you might get lucky and only have to replace them. It isn't difficult if your OK working with electronics and circuit boards. The MOSFETs themselves are pretty cheap and you can probably get them from RS.

I believe the MOSFETs you need are HUF75344G3-ND. They run between $2.00 and $4.00 here in the statea. Here's a Euroloink:

https://cy.rsdelivers.com/product/o...n-channel-mosfet-75-a-55-v-ultrafet-3/8076670

 

[Action]

Were the batteries still hooked up when you took out the PCB (box) ?

 

[HMMWV Sweden]

Were the batteries still hooked up when you took out the PCB (box) ?

Hi Action,,no no no,i disconnected batteries first

 

[HMMWV Sweden]

Update regarding my issues with the waitlight: Measured all the glowplugs,about 1,8 ohms all of them

did some groundchecks and decided to install a ground harness kit from engineblock to..generator,starter,on top of nartronbox and the bolt behind doghouse, like videos on youtube suggest..and my problems are gone...waitlight goes out after 5-10 seconds and starts up right away and runs just fine,,cycling glowplugs,,but for peace of mind i ended up measuring current to glowplugs with ampmeter(clamptype)and they are drawing current when cycling and no current when cycle finished

so the nartronbox lets go of the glowplugs,so i suppose all is as it should be,,most likely poor grounding issues that caused my problems..thanks guys for your support

 

[osteo16]

now if you were so inclined, could pull each of your new grounding harness lines (one at a time) till the problem replicated itself and you will have the actual bad ground culprit.. Just if you were bored and wanted to fix the issue instead of masking it.. That way your new harness would be a nice backup for a functioning system.. Of course Id leave it wired into truck.. Just my 2 cents .. I like original functioning stuff.. OCD !!!!

Ocho out..

 

[Milcommoguy]

now if you were so inclined, could pull each of your new grounding harness lines (one at a time) till the problem replicated itself and you will have the actual bad ground culprit.. Just if you were bored and wanted to fix the issue instead of masking it.. That way your new harness would be a nice backup for a functioning system.. Of course Id leave it wired into truck.. Just my 2 cents .. I like original functioning stuff.. OCD !!!!

Ocho out..

VIVA the HumV.......

This is the best scientific diagnostic statement I have read as to the magical fix for the Humv's. El Conquistador Ocho

Not saying there might be a design flaw or time induced corrosion or a gremlin in the works. Having followed the grounding threads for a number of years and studied the prints, I too would like to pin down the path that is giving some these electrical headaches.

It is interesting to note... I haven't seen a MWO or field / factory fix as to problems that keep popping up here. Installing a addition grounds could be a good idea but doesn't point to the real problem. And like installing one won't hurt, is simple to build and install. Lots of rig dont' have one so what's really going on here????

So is it a work around, band aid, or what??

IMO there as got to be something a little more going on, put one's finger on it, can it be repeated, now I got YA gremlen...AH HA moment to put the OCD to rest.

Take the blue pill or the red/white one or the grounding kit for headaches, CAMO

 

[osteo16]

That would be Conquistador Ocho, not Mr Ocho..

El Conquistador Ocho

 

[papakb]

I've read both pros and cons about adding the grounding harness and my opinion is if the trucks electrical system was perfect from the factory you shouldn't need to add it. HOWEVER, I challenge anyone to tell me that their system was ever perfect and to detail what the military did to your truck over it's lifetime. How much salt water did it see? How meticulous was the maintenence that it saw? Is all the adhesive bonding that was done still in good shape and are all those rivets that connect the panels together still doing their job as intended?

I know for a fact that over the 35 years since the ambulance body on mine was made it's expansed and contracted due to the sun and those very rivets tend to weep if we get a rainstorm. So how do you think they're doing on all those oxidized aluminum panels if they can't keep the rain out? Thank the man I live in California where it seldom rains.

I think the bottom line here is that the only way to guarantee a supplemental harness isn't going to help is to completely dismantle the entire truck, rivet by rivet, bolt by bolt remove every minute bit of corrosion and then put it all back together and then never take it out of the garage again! LOL There's no other way you can be assured you fixed everything that might cause some of the wierd ass problems we see posted here.

Just my 2 cents for the day!

 

[osteo16]

1989 M998.... Went through all my grounds, polished and antisiezed.. Not an issue to date with any Gremlins.. Just my 2 cents.. Guess I'm lucky!!

And Thanks for the edit Gotta love that Bob and Tom

El Conquistador Ocho, out !!

 

[HMMWV Sweden]

Ok guys you all have good points regarding corrosion,design flaws etc...my HMMWV is from 1985 and it´s never a good idea to construct a vehicle that is mounted together with rivets like papakb said...and expect the bodypanels to pass current as good as when new. However when i was istalling the grounding harness i discovered that the groundconnectors on the engineblock and the groundbolt behind the doghouse was heavily corroded,and also the 4 washer/bolts that ground the nartronbox was heavily corroded too,,cleaned those of natrually but i was halfway installing the grounding harness and decided to finish what i started,,but pretty sure that the corroded connectors and bolts is was caused my issues in the first place...but hey if the bodypanels and rivets can´t supply a good ground then you have to help it...dismantling and re-riveting a vehicle to get rid of bodypanel conductivity issues is just not an option..
This can´t be the fist HMMWV with these kinds of problems, i have learnd alot just fiddling around with this and everything works just fine now and that´s the important thing for me. Thank for your input guys.

HMMWV Sweden out

 

[JetbikeAnt]

1989 M998.... Went through all my grounds, polished and antisiezed.. Not an issue to date with any Gremlins.. Just my 2 cents.. Guess I'm lucky!!

And Thanks for the edit Gotta love that Bob and Tom

El Conquistador Ocho, out !!

Same here. Only difference is I use Dielectric Grease instead of Antisieze. I was shocked how quickly the grounding points corroded. Not any more.

 

[Action]

The body is not meant to be a ground. There is sealant between the panels. The grounds are carried thru the hmmwv via wires.

 

[JetbikeAnt]

The body is not meant to be a ground. There is sealant between the panels. The grounds are carried thru the hmmwv via wires.

Basic electronics theory right there. Words to live by.