M37 - Wiring harness and where it goes...

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colin_topliss

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Hi guys,

I am helping a friend restore his M37, and we've hit a bit of a problem. He has an NOS M37 wiring loom, but it does not fit the truck. The distributor wire appears to be on the wrong side of the loom. Tthe loom branches into several legs, and the leg that travels to the front off-side is the one where I'd have thought the distributor wire should lay - instead it is off of the near-side leg not far from where the front harness joins to the rear. The wire is far too short to reach the distributor, and no matter how I try and place the loom it will not fit. Has anyone come across this problem before - because if not we're doing something stupid!

If anyone has any pictures of how the loom should fit that would be really useful (maybe I'm laying it in wrong). Unfortuantely the original loom had been cut, so it was of no real use, and all the manuals we have don't show it in any detail (actually not at all).

Besides which, being an NOS loom, all the printed paper numbers had come off (no metal tags on this one), and the wire sheathing has disintegrated in a couple of places. Not a great day today..... :|

Thanks!

Colin
 

m376x6

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The wiring harness comes out both sides of the firewall. The connector part that attaches to the light control box is the best place to start. Provided you have the correct harness one side will have the distributor wire and horn wire etc, the other side will have the wire for the rear connector and fuel level wire. Also, the drivers side will have the wires that run down to the dimmer switch. Best of luck.

Regards,
M376X6
 

rosco

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I got the full set of "supposedly NOS" harness from Vintage Powerwagon. I had the same sort of problems, but there were many other bugs too. Like a male fitting to go to a light, when it shuld be female, etc. the implication was, that if you layed it out on the floor, it will all hook together and look like the wire diagram in the TM. Far from it! I ended up cutting and splicing /solder & shrinkwrap. Mine was for a "user", so although I didn't like it, it was tollerable.

Lee in Alaska
 

mdog

New member
I bought a NOS wiring harnes for my dodge wc and while testing it with an ohm-meter found two splices in the harnes where the solder had not made a good conection. I suppose it made contact when made but not after 50 years in a box. Otherwise it appears to be of good quality. If your insulation is starting to crumble you might be asking for trouble to even use it. Sorry I can't help more.
 

colin_topliss

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Thanks for your replies!

OK - lets see....

Not sure where he got it from - it was a couple of years ago. It is an old harness though (no metal tags - all paper tags, douglas connectors, was NOS in original packaging, and I think early '50s). Apparently on later looms the distributor cable is a separate extension to the loom?

The distributor cable is on a different leg to the horn. Its closer to the point where the rear harness joins the front. The horn and dimmer switch legs are on the drivers side and look to be in roughly the correct place.

He's going to replace the harness anyway, as the more I looked at it the more problems I saw (mostly where wires left the protective cover of the loom binding). What I was interested in was anyone's experience of bad looms and where it should have gone.

Haven't had this much 'fun' since I rewired the M62..... :-D

I must ask him if he's OK for me to post up some pictures of the restoration - its quite extensive, and it is his first military vehicle!
 

M-37Bruce

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Midlothian, VA
Wiring Loom

Thanks for your replies!


He's going to replace the harness anyway, as the more I looked at it the more problems I saw (mostly where wires left the protective cover of the loom binding). What I was interested in was anyone's experience of bad looms and where it should have gone.

Haven't had this much 'fun' since I rewired the M62..... :-D

I must ask him if he's OK for me to post up some pictures of the restoration - its quite extensive, and it is his first military vehicle!
Vintage Wiring of Maine, definitely the way to go. Please do ask his permission to post a pic or two, we want to see his baby! :wink:

Bye For Now,
 

vtdeucedriver

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Colin you should have sent me a E-mail!!!!!!!!!!!!!!!!!! Colin, you have a early harness, the destributor wire is correct...........thats where on the firewall that it plugs into the Spark suppressor for the radios. then you have another harness that comes across the firewall to the drivers side then foreward to the distributor

The spark suppressor mounts to the right side of the engine block on the firewall.............should be by the horn when the hood is closed.

That was easy/.......................anything else!!!!!

Jeff in Vermont...........................tell max and stuart that I say hi!!!!!! Hows iron butterfly??? Speaking of Gun Trucks....................You guys are building my truck!!!!!!! We need to chat about Red Barron!!!!:)
 
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vtdeucedriver

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John Duncan : photos : Rob Young's M37- powered by SmugMug

Here is a link to some good reference pics.............I use all the time!!!!!

I attached the pic from that site that shows the suppressor. Its the silver box between the air intake and the horn. Its mounted on the firewall. The main harness enters in from the left and then another harness takes the circurit to the distributor.

There was a MWO in the late 50's to remove these from the system. I have retained mine in my restoration. It still works but I have another that I hollowed out and just ran a wire across internally to make the circuit to work.

Glad to help:-D
 

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m376x6

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John Duncan : photos : Rob Young's M37- powered by SmugMug

Here is a link to some good reference pics.............I use all the time!!!!!

I attached the pic from that site that shows the suppressor. Its the silver box between the air intake and the horn. Its mounted on the firewall. The main harness enters in from the left and then another harness takes the circurit to the distributor.

There was a MWO in the late 50's to remove these from the system. I have retained mine in my restoration. It still works but I have another that I hollowed out and just ran a wire across internally to make the circuit to work.

Glad to help:-D

Good call, I had completely forgotten about the older style and the suppressor. Thanks for reminding evryone about that little box. I see so few of those suppressors, I think only once in 25 years. And come to think about it, only one or two of the fuel filters, I mostly come across B series, and the early series I have owned or looked at didn't have either.

Regards,
M376X6
 

Bill W

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Ditto what VT said
I had the same problem when I rewired my 1954,M-37 , the early M-37's ( 1951-2) had the supression filter mounted on the firewall ( later 37's had them mounted in the dist base). Other then adding a extension everything else should be the same. Tell your friend that while he's at it he should run a additional wire to each frt park lights just incase he wants to convert to turn signals, he can just reuse the old B.O brake light wire for the rear.
 
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distributor wire #12

you can buy an extension distributor wire from Vintage Wiring, one end screws on to the distributor the other end is a male fitting that hooks to the main harness (you will need a female tube connector to make the connection work). Good Luck
 

GUNNY 155

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elgin illinois
Almost sound like it is not an M37 harness. I had Vintage wiring of Maine build mine. Simple plug and play. Well worth the cost. They even added a couple of accessory wires I needed for my M151 under dash heater.
 
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