HMMWV Grounding Kit Install

[springer1981]

Not all grounds are equal, CAMO

 

[Milcommoguy]

That's funny but real

If 1 screw is good, 2 must be better and a bolt you decide , CAMO

 

[FunVee]

The grounding harness many of us did, or will, install is a SUPPLEMENTAL harness to the existing factory harness for the most part. While some argue that it should be of a diameter and gauge that can handle the full discharge of two 24V deep cycle batteries, I went much smaller. I found wire that I could afford in bulk at Home Depot and put my own harness together for about $15 start to finish. I don't have the gauge handy, but it was thick enough to be hard to bend into a kink by hand, and it had to be cut with diamond jaw pliers. I made the terminations out of 1.5" lengths of copper pipe of varying diameters, whatever was wide enough to get the wire into and then flatten in the vise and drill a bolt hole through.

Half my problems went away when I installed my harness because the grounding circuit to the instrument panel was loose behind the dash. It turns out that connection has a wire bolted to the engine side of the firewall and another wire lead comes off the back of that bolt inside the cab, then connects to the panel. The bolt on the underside of my dash, on the firewall, was loose. No amount of tightening the other nuts could have helped it. My gauges don't flutter anymore!

Any grounding harness to supplement the small gauge factory one is a good addition. Clean all the connections you touch as you go and you'll improve the effectiveness of the factory harness while adding extra capacity in the form of your supplemental one.

Bulldogger

I found the same issue at the insturment panel grounding screw. I’d recommend anyone installing a grounding harness open up the panel and clean up the grounds on the inside, too. 5 extra minutes of work is all.

 

[Mogman]

I found the same issue at the insturment panel grounding screw. I’d recommend anyone installing a grounding harness open up the panel and clean up the grounds on the inside, too. 5 extra minutes of work is all.

All that is needed is to check the factory grounds, everything on a HMMWV has a return ground wire, the "kit" is not needed, If you had done this to begin with you would have found the issue that the kit did not fix anyway.

 

[FunVee]

All that is needed is to check the factory grounds, everything on a HMMWV has a return ground wire, the "kit" is not needed, If you had done this to begin with you would have found the issue that the kit did not fix anyway.

I agree. Naively, I bought the harness as it was recommended to me to help mitigate potential wiring issues. Searching the web mostly backed up that recommendation. I am one of those fix what you know will eventually break - instead of being broken down - types. So I bought the harness.
After installing the grounding harness and learning more about how the M998 electrical system is set up, I realized how redundant it is. The starter and alternator ground wires in particular. If those are not working correctly a 10ga "helper" wire is not going to do much but turn into a heater. The PCB and dash ground "helper" wires make a little more sense. Otherwise, you are completely right but at worst I am probably out a few bucks and an hour.
Now, on to find the rest of my grounds to clean them up and learn a little more about my M998 in the process.

 

[aconway]

I purchased the Grounding Kit from Kascar (PN 535-A1) and installed it over the weekend. I know it's cheap & easy to make one yourself, but I don't have much wiring experience and for $70 I figured I'd get it right the first time. It was a quick & easy install. Here's a write-up in case it helps anyone out!

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Very nice, thanks for sharing.