HMMWV Grounding Kit Install

[Milcommoguy]

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.

However hard it is to get at, it needs inspecting and better to remove and clean it up. Gauge panel comes out, dog house off or help from the engine compartment. It is a convenient (at manufacture ??) tie point, bringing negative returns back to the batteries negative.


If that connection is hard...wait for the other problems, CAMO

 

[blutow]

However hard it is to get at, it needs inspecting and better to remove and clean it up. Gauge panel comes out, dog house off or help from the engine compartment. It is a convenient (at manufacture ??) tie point, bringing negative returns back to the batteries negative.


If that connection is hard...wait for the other problems, CAMO

I recently went through and cleaned up all my grounds. That spot on the firewall near the heater controls was the only one where I added a supplemental ground back to the engine. It had paint on both sides of the firewall and I did my best to get down to bare metal, it's a tough spot. I'm surprised it was functioning as a ground at all with the thick paint. Figured it was worth adding the extra ground here since I don't want to mess with it again if it can be avoided. I also pulled the grounds to each guage and cleaned/greased them, but I don't think they needed it.



The only other spot I may add a supplemental ground is at the control box since that's also kind of a crappy body connection (as I understand it). I just took off paint down to bare metal for now. If the control box housing is really the only source of ground for the box, that's a pretty crap-tacular design on such a critical/expensive component. Is there really not a dedicated ground connection coming in through the plug?


For these things that are grounded to the body (behind dash and control box), is there a ground strap between the body and engine somewhere? What is the primary path of ground from battery to body shell?

Looking at the previous posts on the Kascar kit, I don't plan to do the supplemental grounds from starter and alternator to the motor. I'm not sure I understand the purpose and it could be dangerous. The starter and alternator already have robust ground connections to the motor. I cleaned the alternator ground strap connections and starter, but don't understand of adding another less substantial connection. For high draw stuff like the alternator and starter, the last thing you want is all those amps running through an unfused 8 guage wire, it would quickly turn into a red hot heating element if the primary ground path had an issue.

Also, I redid all the grounds on the back of my motor and in the battery box. My truck doesn't have any signs of rust or corrosion, but it was a 2009 refurb and they were very generous with the black paint everywhere. Whoever reassembled the motor and connected the grounds did a lousy job of cleaning the paint off and making a good ground point. I cleaned bolts, cleaned up connections and mating surfaces and slathered on some dielectric grease. I pulled that bracket off the head and took the engine and bracket down to bare metal between them. Probably not needed with the current able to go through the bolt, but it never hurts to lower the resistance a bit.

 

[Action]

I recently went through and cleaned up all my grounds. That spot on the firewall near the heater controls was the only one where I added a supplemental ground back to the engine. It had paint on both sides of the firewall and I did my best to get down to bare metal, it's a tough spot. I'm surprised it was functioning as a ground at all with the thick paint. Figured it was worth adding the extra ground here since I don't want to mess with it again if it can be avoided. I also pulled the grounds to each guage and cleaned/greased them, but I don't think they needed it.

View attachment 862077

The only other spot I may add a supplemental ground is at the control box since that's also kind of a crappy body connection (as I understand it). I just took off paint down to bare metal for now. If the control box housing is really the only source of ground for the box, that's a pretty crap-tacular design on such a critical/expensive component. Is there really not a dedicated ground connection coming in through the plug?
View attachment 862079

For these things that are grounded to the body (behind dash and control box), is there a ground strap between the body and engine somewhere? What is the primary path of ground from battery to body shell?

Looking at the previous posts on the Kascar kit, I don't plan to do the supplemental grounds from starter and alternator to the motor. I'm not sure I understand the purpose and it could be dangerous. The starter and alternator already have robust ground connections to the motor. I cleaned the alternator ground strap connections and starter, but don't understand of adding another less substantial connection. For high draw stuff like the alternator and starter, the last thing you want is all those amps running through an unfused 8 guage wire, it would quickly turn into a red hot heating element if the primary ground path had an issue.

Also, I redid all the grounds on the back of my motor and in the battery box. My truck doesn't have any signs of rust or corrosion, but it was a 2009 refurb and they were very generous with the black paint everywhere. Whoever reassembled the motor and connected the grounds did a lousy job of cleaning the paint off and making a good ground point. I cleaned bolts, cleaned up connections and mating surfaces and slathered on some dielectric grease. I pulled that bracket off the head and took the engine and bracket down to bare metal between them. Probably not needed with the current able to go through the bolt, but it never hurts to lower the resistance a bit.

View attachment 862080

View attachment 862081

The body is not used as a ground. You do not need to clean paint from the PCB bolt or behind the dash. The bolts at both locations carry ground to the other side.

 

[blutow]

The body is not used as a ground. You do not need to clean paint from the PCB bolt or behind the dash. The bolts at both locations carry ground to the other side.

Thanks, I was suspect that they were actually ground points (particuarly on the PCB), but I see folks adding a ground to these points with the kits. So where is the breakdown in the ground path that is pushing folks to use these kits (with positive results it seems)? If the motor is well grounded and the ground connections to the motor are good, I don't really understand what else is in play.

 

[Action]

Thanks, I was suspect that they were actually ground points (particuarly on the PCB), but I see folks adding a ground to these points with the kits. So where is the breakdown in the ground path that is pushing folks to use these kits (with positive results it seems)? If the motor is well grounded and the ground connections to the motor are good, I don't really understand what else is in play.

The connections get cruddy. That bolt in the firewall just connects the wires on one side to wires on the other side. The firewall could be wood but the parts need to be clean and make good contact.

 

[blutow]

The connections get cruddy. That bolt in the firewall just connects the wires on one side to wires on the other side. The firewall could be wood but the parts need to be clean and make good contact.

Yep, I totally get that now, but why are people buying kits and running a supplemental ground wire from that point to the back of the motor? I see posts about these ground kits being needed because of the hmmwv's aluminum body. Which makes zero sense me, espcially when you say there are not any body grounds being used (which is good design). If all the grounding to each component is done via dedicated wire runs, I'm struggling to understand the point of these supplemental ground harnesses. If I didn't see a bunch of folks saying it solved their problems, I'd think they are snake oil. Maybe the harnesses are just solving problems because people are cleaning their primary grounds when they install them? Just struggling to get my head around these grounding issues that seem to make expensive stuff break.

 

[Action]

Yep, I totally get that now, but why are people buying kits and running a supplemental ground wire from that point to the back of the motor? I see posts about these ground kits being needed because of the hmmwv's aluminum body. Which makes zero sense me, espcially when you say there are not any body grounds being used (which is good design). If all the grounding to each component is done via dedicated wire runs, I'm struggling to understand the point of these supplemental ground harnesses. If I didn't see a bunch of folks saying it solved their problems, I'd think they are snake oil. Maybe the harnesses are just solving problems because people are cleaning their primary grounds when they install them? Just struggling to get my head around these grounding issues that seem to make expensive stuff break.

The ground harness cant hurt. I see them like a bandaid. My truck works great without one.
The wire to the PCB bolt will pass thru the bolt and into the chassis of the box. That will only help if internal items are grounded to the shell.

 

[blutow]

The ground harness cant hurt.

In some cases, that's true. In good electrical design, I believe it's best practice to have a single path back to ground where possible. There are multiple reasons for this. Multiple ground paths can create ground loops, which can create electrical problems and interference. It's probably not a big deal on these basic trucks, but ground loops should still be avoided when possible.

The big issue I see with these ground harnesses is going back to the starter and alternator and potential safety issues. An alternator has a huge ground strap on it because it can put out 200a continous. That's a ton of current. Look at the size of the positive wire going into it. A ground/negative has to carry just as much current at a positive wire, it's always a round trip to the battery. By adding another ground to the alternator, you just created an alternate path. When your big OEM alternator ground connection is working as designed, the second ground is not a problem because the bulk of the current will follow the path of least resistance. If you develop a bad connection with your original ground, the current will want to run through the smaller wire. If the original ground fails completely, all current will be running through the secondary ground. Try running 200a continously through an 8 or 10 guage wire and things will go bad in a hurry.

Again, I'm not saying these ground harnesses don't have a place, I'm just trying to understand the point of failure in the HJMMWV's that is causing folks to install them. If ground is taken off the back of the engine for the stock wiring harness, where is the bad connection betwen that point and all the components that seem to be having ground issues? Is there an intermediate negative bus bar somewhere that is causing a breakdown in the circuits? Where is the the breakdown happening in the OEM wiring?

I really think the extra alternator ground (in particular) is a safety issue, but I might be missing something there also. The starter less so since I assume the entire starter housing is grounded to the engine and it's very unlikely that ground can be broken. I suspect the alternator might be grounded via it's mounting brakets as well, but it's just bad practice to put a tiny ground wire to a component that has a huge potential load. If you want to add another ground, best practice is to make the ground/negative as large as the positive wire.

 

[Milcommoguy]

STOP calling it a ground. LOL... Last time I say this... HMMWV's..., All the electric business has it OWN negative return lead back to the battery negative. Look over the schematic and one will see what I speak of. NO currents flow thru the frame, body or what you had going on in the 57 Chevy.

Lets start from the front, fiberglass hood (clue here)... Headlights, turn signals, markers, black out, plastic or metal housings have a return wire to battery negative thru the harness.

Jump to the rear...same here. Tail lamps, plastic or metal, mounted in a plastic bucket. Each lamp assembly has a negative return wire to the battery negative.

You might not see them...BUT there are many spliced together internal to the harness design. Has for the plastic lamp assembly (the $$ cool ones) you will need to have the mounting strap in place. Various designs use just one mounting bolt to connect internals. Problems show up here ALL the time. Leave it off and guess what. YEP, no negative return with lighting circuits back feeding thru lamps working all wonkie. That's an electrical term for WTF.

Back to center...Looking for the engine ground strap? Nope, Negative return is the BIG fat negative wire on the starter, from the battery and going all which ways. Up to the alternator, engine head, and over to the PITB 1/4 inch bolt.

This bolt called Body Gerrroung and another one called Column Gerrroud are not Grounds. I can't say it. They are convenient TIE point to bring the various individual harness assemblies negative leads with a lug for assembly, a hard point that happens to be metal. The steering column, control box and horn have there own wire to this point under the dash, again spliced together. All of the dash gauges and lights same thing. Say it "negative body tie point"

WHEN thirty years of ware and tear, chemicals and corrosion get between these lugs... all things electrical can go wonkie. Clean them up and see where your at. IF for some reason that doesn't get it...YOU MAY have one of the internal splices going bad. I have torn into the harnesses and they are crimped, soldered, wrapped and sealed very very good. Just know there are some positive one in there too. Positive branch circuits feeding IP, fan control, kick down, cold advance, etc.

Benjamin Franklin had a ground. HMMWV a return. Don't get me started on the shunt, LOL... CAMO

 

[blutow]

STOP calling it a ground. LOL... Last time I say this... HMMWV's..., All the electric business has it OWN negative return lead back to the battery negative. Look over the schematic and one will see what I speak of. NO currents flow thru the frame, body or what you had going on in the 57 Chevy.

Lets start from the front, fiberglass hood (clue here)... Headlights, turn signals, markers, black out, plastic or metal housings have a return wire to battery negative thru the harness.

Jump to the rear...same here. Tail lamps, plastic or metal, mounted in a plastic bucket. Each lamp assembly has a negative return wire to the battery negative.

You might not see them...BUT there are many spliced together internal to the harness design. Has for the plastic lamp assembly (the $$ cool ones) you will need to have the mounting strap in place. Various designs use just one mounting bolt to connect internals. Problems show up here ALL the time. Leave it off and guess what. YEP, no negative return with lighting circuits back feeding thru lamps working all wonkie. That's an electrical term for WTF.

Back to center...Looking for the engine ground strap? Nope, Negative return is the BIG fat negative wire on the starter, from the battery and going all which ways. Up to the alternator, engine head, and over to the PITB 1/4 inch bolt.

This bolt called Body Gerrroung and another one called Column Gerrroud are not Grounds. I can't say it. They are convenient TIE point to bring the various individual harness assemblies negative leads with a lug for assembly, a hard point that happens to be metal. The steering column, control box and horn have there own wire to this point under the dash, again spliced together. All of the dash gauges and lights same thing. Say it "negative body tie point"

WHEN thirty years of ware and tear, chemicals and corrosion get between these lugs... all things electrical can go wonkie. Clean them up and see where your at. IF for some reason that doesn't get it...YOU MAY have one of the internal splices going bad. I have torn into the harnesses and they are crimped, soldered, wrapped and sealed very very good. Just know there are some positive one in there too. Positive branch circuits feeding IP, fan control, kick down, cold advance, etc.

Benjamin Franklin had a ground. HMMWV a return. Don't get me started on the shunt, LOL... CAMO

I get it to a point and I fundamentally agree with what you are saying, but "negative ground" is pretty standard automotive vernacular even in systems that have dedicated negative runs to everything. Also, the hmmwv (and many modern vehicles) still have a negative "ground" at the engine. The motor is basically acting like a big secondary negative buss bar if you prefer that terminology.

If folks are having breakdowns in their negative wire runs where they branch, a secondary harness could help with that. Normally, you would not want to create multiple return paths, but if one path is proven to be problematic and can't easiliy be fixed, then putting alternate paths in place makes sense. I still don't agree with the secondary starter and alternator grounds (their primary negative paths are very simple and robust), but would love to hear an argument for why it makes sense.

 

[Milcommoguy]

I get it to a point and I fundamentally agree with what you are saying, but "negative ground" is pretty standard automotive vernacular even in systems that have dedicated negative runs to everything. Also, the hmmwv (and many modern vehicles) still have a negative "ground" at the engine. The motor is basically acting like a big secondary negative buss bar if you prefer that terminology.

If folks are having breakdowns in their negative wire runs where they branch, a secondary harness could help with that. Normally, you would not want to create multiple return paths, but if one path is proven to be problematic and can't easiliy be fixed, then putting alternate paths in place makes sense. I still don't agree with the secondary starter and alternator grounds (their primary negative paths are very simple and robust), but would love to hear an argument for why it makes sense.

Wasn't looking go to the wall on wiring, but to point out wiring unique to HMMWV that one may run into. Here we GOoo, Not sure... Break out the TM's

I agree with you TOO.

With a electronics back ground, is that one or two words... LOL I am careful to identify what are grounds and as to the reference point that circuits return on. Here it is simple DC and the return is not referenced to the metal chassis components. This "floating" ground as thrown a "LOOP" for some chasing electrical issues. (Reading between the lines and I know your getting this lol)

That all I was pointing to. Yes, the quick fix harness could be a workaround. I am pretty sure that just getting in there and cleaning them up word be the fix. Some VODOO gremilns going on here ? For me... I like to put a finger or a meter on it to be sure.

Tomato-Tomato...Is it soup yet, CAMO

 

[rolling18]

What diameter is the main connection on the rear cylinder head? Is that also a 3/8 hole? Thanks for the pictures, looks great.

great info is this for all generations of hmmwv?

 

[Mullaney]

great info is this for all generations of hmmwv?

.
Best thing for you to do is to "Do The Time". You have already done the crime (so to speak). It isn't sexy. It won't be fun. To be honest, nobody but you will ever know that it was done... Sad really.

The thing to do is remember that you have a twenty year old truck. It was built for a purpose. It wasn't stored in a garage. The guys and gals that used it didn't own it and most of them drove it like they stole it. Maintenance in a lot of cases were "break fix" repairs. If it cranked and ran, it got used. Windows were rolled up if the driver was in the truck and sand was blowing or it happened to be raining. Otherwise, it got parked with the windows up or down to it's last use.

So, after all the rambling:
Get yourself a tube (or spray can) of Anti-Oxidation paste and a few old toothbrushes. Might even want to get a brass brush or two. Maybe start on the batteries. Disconnect them, clean and use Anti-Ox on them and all the connections on the batteries. ANYWHERE you see a wire attached to something, disconnect it, clean it, add Anti-Ox, then put it back where it came from.

Then, early one Saturday morning - Disconnect the Batteries - and Start at the front or the back of the truck. Disconnect each wire one by one - Remove it, Clean it, Anti-Ox it, Put it back. It will take all day to do about half of the truck... Again, no fun but remember it is a twenty something year old truck. Give it some TLC and you won't waste your money on a Ground Kit.

 

[osteo16]

DITOES to MULLANEY... And the grounding kits are only gonna fix the ground for the major components.. PCB, Starter, ALT, Batteries... .... Not gonna fix your instrument cluster, not your lights, not your turnsignals, not your brake lights, not your wipers... ECT ECT .... Polished most of my terminals front to back, probably had 10-15 hours in it... TIME well spent.. ZERO GREMLINS.. FWIW...

Ocho

Disconnect your batteries first

 

[CarmelIndianaHMMWV]

Hope this is the right place to post. I know it's not called a ground, but I'm calling it that. M1151a1 was missing the water crossover. Got the crossover and associated parts. Now, trying to figure out the alternator ground strap, and another ground wire from the harness labeled 3a. Some pics I see the strap/ribbon bolts to the crossover stud. My crossover has a stud closer to the thermostat. Is that correct?

Is the black 3a OK to stack on the ribbon?

There is another possible point on the block, right behind the crossover root connection.

Thanks

 

[Milcommoguy]

Hope this is the right place to post. I know it's not called a ground, but I'm calling it that. M1151a1 was missing the water crossover. Got the crossover and associated parts. Now, trying to figure out the alternator ground strap, and another ground wire from the harness labeled 3a. Some pics I see the strap/ribbon bolts to the crossover stud. My crossover has a stud closer to the thermostat. Is that correct?

Is the black 3a OK to stack on the ribbon?

There is another possible point on the block, right behind the crossover root connection.

Thanks

Not the answer your looking for BUT I would put this in the HumV file.

https://www.steelsoldiers.com/attachments/military-wire-id-tag-codes-pdf.662270/

It will come in handy... like a ______________, CAMO

 

[CarmelIndianaHMMWV]

Not the answer your looking for BUT I would put this in the HumV file.

https://www.steelsoldiers.com/attachments/military-wire-id-tag-codes-pdf.662270/

It will come in handy... like a ______________, CAMO

I appreciate it. I've heard of this list, but didn't know where to find it. I'll save it.

So my wire says 3a. The list just shows #3 and lists it as "generator ground circuit".

I guess my question is where do I attach wire 3a, coming out of the harness and the ribbon from the generator? Would you possibly have a diagram available, or could you point me to the location in the TM?

Thanks again

 

[Milcommoguy]

I appreciate it. I've heard of this list, but didn't know where to find it. I'll save it.

So my wire says 3a. The list just shows #3 and lists it as "generator ground circuit".

I guess my question is where do I attach wire 3a, coming out of the harness and the ribbon from the generator? Would you possibly have a diagram available, or could you point me to the location in the TM?

Thanks again

I don't have that set up. Someone else should be hoppin in soon.

Not all grounds are equal, CAMO

 

[CarmelIndianaHMMWV]

It's a 400 Amp generator if that helps.

 

[GTUnit]

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