HMMWV Grounding Kit Install

papakb

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Conventional thinking is that current is the flow of electrons from negative to positive. The purpose of the grounding kit is to eliminate potential differences ideally there shouldn't be any current flowing in the ground system.
 
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scottm122606

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Hi there, new to the forum. Purchased the same Kascar wire harness and will be cleaning the existing terminals and installing the Kascar over the weekend. I have the flickering lights and gage issues to say the least.

My biggest problem is cold hard start. Did replace the glow plugs, put a block heater, etc. and still won't fire up right away!! Once I deal with the grounding, I'll then proceed to disconnect the battery and install a replacement controller. (I think my Nartron white label smart start system is still ok) I'm hoping these couple of quick and easy steps can help remedy the problem. Shouldn't have these issues firing up when the weather is only 45 degrees.

Anybody have some input regarding my plan? Other suggestions? P.S. gonna replace the thermostat, seal, flow control switch, and radiator cap shortly after.... simple jobs turn into projects man! (1990 M998)
 

Dock Rocker

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Hi there, new to the forum. Purchased the same Kascar wire harness and will be cleaning the existing terminals and installing the Kascar over the weekend. I have the flickering lights and gage issues to say the least.

My biggest problem is cold hard start. Did replace the glow plugs, put a block heater, etc. and still won't fire up right away!! Once I deal with the grounding, I'll then proceed to disconnect the battery and install a replacement controller. (I think my Nartron white label smart start system is still ok) I'm hoping these couple of quick and easy steps can help remedy the problem. Shouldn't have these issues firing up when the weather is only 45 degrees.

Anybody have some input regarding my plan? Other suggestions? P.S. gonna replace the thermostat, seal, flow control switch, and radiator cap shortly after.... simple jobs turn into projects man! (1990 M998)
My guess is your glowplugs are already toast. You should do the harness and the control box before you replace the GP’s. If you have bad grounds and / or a bad box the GP’s will burn up no matter how new they are.

I wold put a meter on your current plugs and see how many are burned out. Then put the harness on and a new box then New GP’s. Don’t forget to disconnect your battery before you start working on the Smart box.

At that point I bet your hard starts will go away.


Sent from my iPhone using Tapatalk
 

scottm122606

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Thanks for the input, much appreciated. Gonna get started tonight into tomorrow. Will check the plugs, hopefully they are not fried because I replaced them a few weeks ago.

Just to clarify I am only replacing the controller, not the paired KDS box with controller. I have a white label newer Nartron and have the compatible Nartron TSU. If all my effort avail the same condition I will man up and buy the KDs box. (I hear it fixes everything 🤔)
 

scottm122606

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Quick update regarding my 1990 M998. Kascar grounding harness now installed. As my plugs are toast (new Diesil Rx ones on order), and I am waiting on the KDS S3 box with compatible TSU. I will probably replace the thermostat and seal just to get that out of the way before I start on the glow plug circuit.

What is the easiest way to test the wires to glow plugs before I do everything else?
 

scottm122606

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Thanks. The thermostat flow control didn't apply to this vehicle. Application was on a commercial H1, not military. Vehicle is working great after replacing the Nartron S3 with a KDS box. All glow plugs were fried and I replaced them. No further issues at all.
 

Makis96

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One additional step I took when adding the grounding harness was to spay the connections with plastic dip to seal out water. Hope this helps prevent future issues.
 

Mogman

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Does anyone know if there is a frame ground cable and where it attaches to and from? I see one for the body and of course the engine but I do not see one to the frame.
 

papakb

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There is no frame ground tie point in the supplemental harness but it wouldn't hurt to have one. Nothing else in the truck grounds to the frame.
 

Mogman

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Thanks, I am a little surprised there is no factory frame ground and adding one would be a really good idea especially when mounting an electric winch otherwise much of the current for things like a winch can travel through the shafts and bearings, of course a ground should be run from the winch also but still a little added protection can't hurt, could also reduce radio interference.
 

papakb

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The non-hydraulic HMMWV winches have 2 high current cables running to them. Typically both cables run to the starter. Nothing relies on the frame as a return path for current. Because of the way the truck is constructed everything in the HMMWV either has a ground connection in the wiring harness or runs a separate heavy gauge wire to a negative battery connection.
 
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Starlight

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Ok, I'm sure I'll catch some crap from some on this (and yes, it's deserved). I was all geared up to install new grounding kit on a Sunday morning. Opened up everything on truck and see it has already done apparently during the Maine rebuild. Just a note to see if you may have already. It will be in the wiring looms with other wires, nicely done. Capt. T
 

papakb

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Something you hardly ever see mentioned in the numerous postings abour hard starting HMMWVs is people checking the COLD ADVANCE SWITCH and it's associated SOLENOID in the injector pump. Two critical components in cold weather starts. The cold advance switch is on the rear end of the right cylinder head and is easy to test with a multimeter. The IP solenoid should click when the start switch is activated to allow more fuel into the cold engine. It's a common failure because it doesn't cycle if it's warm outside so they get sticky over time.

Cold advance switches usually run under $50 online and the solenoids are under $100.


Cold Advance Solenoid.jpg
 

Hummer Guy

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So, I finally got around to putting my grounding kit on and one thing I notice is that the ground on the body is extremely hard to get too, I found another spot to ground the new body harness too, can I put the old harness on top of the main ones with the engine?
 

Action

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So, I finally got around to putting my grounding kit on and one thing I notice is that the ground on the body is extremely hard to get too, I found another spot to ground the new body harness too, can I put the old harness on top of the main ones with the engine?
There is no body ground on the hmmwv. The spot on the firewall is a connection for the stuff in dash. It just happens to go thru the body.
 
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