“I thought somebody was BBQing” / New 2006 M1097R1 owner looking for direction for an electrical issue.

[Ramzi]

This evening I took the dog box off and noticed a disconnected ground which comes from the TC light. I set it against the block then took a call from my wife (mistake #1) and all of a sudden the ground wire on from the firewall 3C melted through the insulation - I believe this is the BODY ground.
The funny thing (not haha funny, more ironic funny) is that I had no power on ("key" was off), nothing was touching the batteries, the only change was pulling the dog box off.... oh that and the wife calling.

My question is - where is the best place to find a wiring schematic for this truck.
Any recommendations where to look first?

BTW - just a bit of advice - make sure you have a fire extinguisher mounted at home. I have 2 but couldn't find either when this happened

 

[Mogman]

Welcome to the SS forums!!
3C is the gen to body ground, what is the small wire number? what was it connected to?
Also it would be helpful if you include the model number of your truck

 

[Ramzi]

Coming from an automotive world (albeit Italian) I should have known to include more information. And I appreciate the gracious way you asked.
Vehicle is an 2006 M1097R1
The wire which melted is connected to the ground on the firewall - marked as 3C. There are no other wires on that terminal. The small wire is the bare wire and what looks like the large wire in the photo is the insulation.

Since as you say it's a body ground - my plan is to start at the rear of the truck and work my way to the front taking components off testing, cleaning and regrinding them. My guess its something simple but will take a little time to find.

I suppose my general question might be - are these trucks electrically finicky like British cars? or am I just lucky today.
Not complaining - still getting the feel for them

TIA
r-

 

[Mogman]

Yes they are somewhat finicky, mostly caused by bad ground connections.
Start at the batteries and check the large cables first, there are bulkhead connections though the battery box that should be checked/cleaned on both sides, then the ground cables to the starter and the back of the engine block, alternator.
Be vary careful if you check/clean the positive cable to the solenoid on the starter as that connection is in plastic so careless over torquing for example can break the solenoid.
I am concerned that you said nothing was turned on at the time the wire melted, did it spark when you connected it? what did you do just before it melted?
Is/was the truck able to run before this happened or are you just now working towards getting it running?

 

[Ramzi]

I am concerned that you said nothing was turned on at the time the wire melted, did it spark when you connected it? what did you do just before it melted?
Is/was the truck able to run before this happened or are you just now working towards getting it running?

Thank you for being understanding. I come from the world of FIATs (Fix It Again Tony) and we have our share of electrical issues. Mainly they are ground related. Only once in my (long) life have I had a wire glow an release smoke before my eyes in a car. That was 40 years ago in a 240Z.

I honestly dont think I touched or moved anything to cause this but clearly I did. I'll start at the batteries and work my way from there. Im thinking of fitting a Kascar body ground harness to augment the grounding system.

My fear is that something downstream is cooked. I know this is a stretch and I hate it when ppl ask me this question. Are there any "sensitive" electrical components on that 3C ground I should look out for? Should I disconnect a few black boxes before going any further?

Oh and the truck was running fine before this. The only reason I opened the DB was because it smelled of fuel and sure enough the "valley" had a puddle of diesel. So the pump is likely nest. In my world we call this the cost of entry - not sure what HMMWV folks call it. But it sure beats my day job!



Thanks in advance!!

r

 

[Mogman]

I am not a big fan of the supplemental grounding harness, IMHO it can create unintentional ground loops that can cause problems.
Everything on a Humvee has a specific ground path, the body itself is not used for grounding, everything grounds through a small number of grounding points.
The plan should be to work with the larger cables first.
All this is laid out in the schematics in the available for download for free here on the site.
https://www.steelsoldiers.com/threads/hmmwv-technical-manuals-if-you-need-it-its-here.189594/
Use the information for the M1097A1, it is the closest to your R1 that is out there.
What part of Texas are you in?

 

[Ramzi]

Roger that - stick to the basics. The simplest solution is usually the best.... Just printed a blow up of the 1097A1 schematic from the TM. I'll start by squaring up the existing connections then get the volt meter out and "pull wire" as we say. It's honestly amazing how much detailed information is out there on these vehicles.

Im in Grapevine - basically the middle of DFW... yourself?

 

[TOBASH]

Referring to your title OP:

Please find friends with better BBQ skills.

 

[Ramzi]

So the plot thickens ...

I pulled continuity on some wires and the large 3C ground seems to become part of a larger ground headed towards the drivers side of the motor.

Which is when I noticed the wire going into the back of the regulator (photo attached). All the other wire connections on the truck appear in good condition… so I believe when I owned the hood & removed the dog box I must have moved the connector enough to cause a short.

So here are a couple of questions.

1) If Im so lucky as to NOT have roasted my regulator or alternator, how do I replace this plug? I tried taking it apart only to nearly destroy it.

2) Is there someone recommended to test and or rebuild these units (alt and/or regulator?

TIA

r-

 

[Ramzi]

Not that anyone cares.. but this Cannon plug is a bugger to track down.
Best Ive been able to find so far is MS3106A16-9S from Newark.
Good news it worked and my charging system seems to be "un-fried"
Next - re-ground everything!!!

 

[Ramzi]

The next plan is to augment the existing grounds.
From what I can see - and this seems common to all "older" vehicles, the grounds seem to degrade at their contact point over time.
Im my case and 10AWG wire was the weakest link and let the smoke escape... so where adding a supplemental ground to that main harness as well as one from the body to the engine assembly

 

[Mogman]

The next plan is to augment the existing grounds.
From what I can see - and this seems common to all "older" vehicles, the grounds seem to degrade at their contact point over time.
Im my case and 10AWG wire was the weakest link and let the smoke escape... so where adding a supplemental ground to that main harness as well as one from the body to the engine assembly

Fix the factory grounds and you will be fine, adding more grounds creates ground loops and more "weak" links IMHO

 

[Ramzi]

Well I would but the factory 3c ground became so hot that its now brittle to the point where it connects the main harness.
Ive spliced in a new mil spec 10AWG wire but for my money thats not good enough because a spice creates an additional point of failure. So supplementing that route (harness to body) cant hurt anything.

 

[Milcommoguy]

HEADS-UP to 3x wires on 1097R1 trucks from GL looking to ground the alternator. Seems some experts have connected it to the IGN sense on top of the 5A x wire.

This is a FIRE and a TOASTED controller the instant one goes from STOP to RUN. This picture is as received from GL... And YES it smoked. along with a hand full of 57X and 58x wires. One might check if new to the HumV.

In the firehouse, CAMO

THIS PHOTO IS WRONG **** 3B to ground NOT to 5A. 2A OK

 

[Ramzi]

Dang good advice sir! Much thanks for that!
Im checking the wiring diagram next. I think 3C (my culprit) ties into 3B at the alternator.
Will verify in the daylight

Thanks for that

 

[Ramzi]

Not that anyone is following this but I did get it sorted. Took an act of congress to find the cannon plug - (MS3106A16-9S or ending in P) but they are available on Ebay for about $25.

 

[TOBASH]

Not that anyone is following this but I did get it sorted. Took an act of congress to find the cannon plug - (MS3106A16-9S or ending in P) but they are available on Ebay for about $25.

Great work!

(Congress sucks.)

 

[Mogman]

Not that anyone is following this but I did get it sorted. Took an act of congress to find the cannon plug - (MS3106A16-9S or ending in P) but they are available on Ebay for about $25.

That plug shorting out is fairly common, this info will help!