Civy truck to MIL trailer wiring info

charlietango

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The 7812 is a simple voltage regulator IC in a TO-220 package.


If it's a newer-style electronic one, you need to use a DC-DC converter ahead of it, to feed it 12V.
This part available anywhere or is it a Military part? sounds like the way to go after all especially cost wise...

and RGR my brake pack is a newer style but thats the reason I bought the DC DC converter mostly. I just wired up an 8 bus fuse panel giving me 8 12V splits. so here is my plan based on your info.

I will split off the military wiring harness the running lamps and signal lamps and stop lamps with the 7812's and wire in a seperate civi trailer harness to the rear chasis somewhere.
the brake pack will run off the DC DC converter receiving 12V. I will take a second split off the brake lamp line and run it through a 7812 into the brake pack to supply the trigger. Then run an independent line for the trailer brakes to the new civi harness. is BOB my uncle? kind of confusing trying to wrap my head around this one..
 

ecostruction

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Is there a ground going to the tail lights on a deuce? Or are they grounded through the truck. Or, maybe I should be asking if lights off a M105 are ground through the trailer?

I've been looking but can't determine.
 

Numbers

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Grounding question...

Is there a ground going to the tail lights on a deuce? Or are they grounded through the truck. Or, maybe I should be asking if lights off a M105 are ground through the trailer?

I've been looking but can't determine.
According to TM 9-2320-361-20: Electrical diagram foldout
http://old.steelsoldiers.com/index.php?module=pagesetter&tid=1&page=9

There is a self ground on the lights. The trailer receptacle pin D (wire #90) is a chassis ground.
 

Militoy

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This part available anywhere or is it a Military part? sounds like the way to go after all especially cost wise...

....
The part is readily available from any electronic supply house - Digikey, etc. You could probably even pick them up at Radio Shack. Like any electronic part, you might need a little guidance using it, unless you're an electronic hobbyist, a Ham Radio Operator or a technician.

Don't know what's available in Manitoba - I know Vancouver is pretty much like Seattle, business-wise. Post here if you need help getting or using the parts - and I'll help out as much as I'm able.
 

charlietango

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ok i have a few places in winnipeg i can check...might have to hit you up on that install help yet. I get by but am self taught...love the challenge though !
does my plan for using them sound right?
 

KsM715

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emmando22, the thumbnail attatchment you have in the original post, is the round part with the pin letter arangement, is that looking at the truck receptical or looking at the intervehicle connector. I got the trailer connector a guy cut off a 105 trailer last night and need to wire a 4flat to it so I can connect some magnetic trailer lights to it for towing civy stuff with my M818
 

emmado22

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The pin letter assignments are embossed in the rubber that the connector is made out of (That houses the pins themselves) Clean up the connector, you should be able to see it.
 

KsM715

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Thanks it was full of cob webs when we cut it off and was pouring rain when I got home so I never even looked at it.
 

tuckered

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I have a M-101 A1 trailer. I bought it for its off road capabilities from Govliguidators. It had brand new tires, bows, racks, pig-tail and wiring harness. etc. The trailor itself was about the only used part on it. (The tires still had the stickers them, but had no spare).

Long ago, I had acquired a harness that was attached to an old scrapped out military vehicle. I intend to make an adapter to plug the trailor into my civie truck, so I could use the military harness. Thanks to the ealier posts about which wires to connect, I might be able to figure it out. (Thanks by the way).

My electrical knowledge is small, I just know that 220 volts hurt! and thats about it. Now for my problem. . . what bulbs would I use, to replace the 24 volt bulbs for use with/for a 12 volt bulbs/system? I want to keep using the military trailer lights, just because they are new and look neat, even though I can't use the blackout lights. I'd rather not replace them with a China made Wal-mart trailer light kit.

Also, if I replaced the regular bulbs with a 12 volt LED bulb from local auto parts store (of the same type), and later connected it to a retired military vehicle, would it blow the 12v, LED bulbs?

Thanks!
 

UNIMOG-GUY

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You know I bet if someone were to make 2 basic conversion plugs (Civi to Mil & Mil to Civi) they could sell however many they made. I'd buy 2 right now.
 
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tuckered

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If a person had a place with scrapped out military vehicles, they can make some money off this.

In case of a scrapped trailer, selling the pigtail harness, with maybe a couple feet of wire attached and incase of a vehicle, selling the harness with foot of wire attached, as well.

From there, the buyer could wire it how they like and with whatever connector they want.

I "borrowed" a vehicle harness from a junked out/scrapped out sellf-propelled howitzer from some place. If the military ever wanted to reactivate the demilled and rustout out thing, I will happily return it for free. In the mean time, they are letting me borrow it (with the proper permisions of course).

I could go to wal-mart and get a new trailer wiring harness for $30 or so. Big deal. I want to use the orignial military trailer harness, just for the fun of it and for the priniple of it. The only info I need is what type of light bulbs to use, for the trailer lights on a 12 volt system.

I found out too, that it was cheaper, in Missouri, take my wonderful trailer to the Highway Patrol, along with my purchase reciept, pay a $10 fee and get my trailer titled that way, rather then waiste 4 months for GOVLIQ to send me a title, after I pay them a usery fee of $70.:jumpin:

I don't know if that works for a vehicle or not, but I will eventually find out. :driver:
 

jimm1009

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I normally don't like to inject confusion into an issue but anyone wanting to use a civy trailer as an example on both their civy trucks and 24 volt military trucks must remember one thing.
Simply changing the bulb from 24 to 12 or 12 to 24 is not the only requirement.
Using the 12 volt industry standard number 1157 bulb as an example;
The bulb is wired so that one filimament is brighter than the other hence the brake & turn being brigher over the other filiament in the same bulb being dimmer for the tail light. When you switch from 12 to 24 volt vehicles and you install the 24 volt equivelant of the 1157 you must also switch wires between brake/turn and tail. If you don't then the brake light will become the dimmer filament and the tail light will become the brighter filiament which is not correct and very unsafe.
The military overcomes this problem by having seperate bulbs for the seperate functions. This way the bulb only has to be switched to the proper voltage depending on the tow vehicles system voltage. The dimmer bulb is always the tail light and the brighter bulb is always the brake & turn as applicable.
The same applies for some of the LED tail lights so you have to be careful of which ones you purchase.
Bottom line is when you are done swapping trailers that have civy lights on them from one system voltage to the other be sure to make sure that the brake / turn is still the brighter set of led lights or brighter filiament and the tail is the dimmer set of lights or filament.
I have seen guys & gals driving down the road with what appears to be their trailer brake lights on all the time and then when they actuate the tow vehicle brakes you generally don't see the brake lights come on which could potentially be a problem for the vehicles behind him or her.
I only bring this up as a safety issue as we all want to be extremely safe while we promote our hobby to others.
Think O.D. Green!

Thought about it for a day or so and I want to calrify what I wrote earlier; If you have an 1157 bulb installed (12 volt) and you put the 24 volt bulb in it's place you have to swap the wires to make the bulb function properly. I do not have experinece with the LED lights but I would imagine that the same problem will exist if you swap from 12 to 24 volt systems.
Hopefully someone with dual votage LEDs will chime in here.

jimm1009
 
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namedpipes

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. . .

Here is the info you need to know.

Civilian trailer wiring

Green wire = Right turn/stop light
Yellow wire = Left turn/stop light
Brown wire = Tail/marker/running lights
White wire = Ground

Military harness circut # and Pin
22-460 Pin J = Right turn/stop light
22-461 Pin B = Left turn/stop light
21 Pin E = Tail/marker lights
90 Pin D = Ground

Important note: Do not use circut 37/Pin K for a ground. Many times it is terminated and not connected to the trailer chassis. Circut 90/Pin D is ALWAYS the mil trailer ground.

. . .
So I finally got off my butt and wired up a 4-way to milspec harness adapter.

My current tow is a 91 Dodge 3/4 with a pintle hook mounted where the plate normally goes, plate relocated to the bumper. (and then a ball hitch on the frame underneath for the "little" trailer). The 24v bulbs are a little dimmer than they should be but work. The lamp assembly doesn't look inclined to come apart to change the bulbs to 12v ones, so they will likely stay 24v. The plate will be lampless, but if I find a need to drive at night I'll stick a flashlight on with duct tape.

Since my future tow is a Deuce I wanted to leave the trailer stock and made up an adapter. One of the threads here pointed me to a source for the part, meant to bolt to the bumper, I suppose. Mine wound up as a pigtail.

The wiring connector on the truck didn't match ANYTHING, but I was able to deduce what was what using a funky 4-way from wallyworld that has leds telling you what is lit.

So, thanks for the color coding, pin #s. It saved me a bunch of time! And best of all I found out using 'search'!!
 
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Fudge0514

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Another similar pre-made harness, for about $72 as of Sept 18, 2011: http://www.eriksmilitarysurplus.com/mitradcamtro.html

--------------------------------------------------------------------------

Found the electrical receptacle MS75021-2 as referenced in the first post on ebay for $12 buy it now (and $3 more for shipping).

Coiled wire adapter for $12.99 (+$6.95 shipping) on ebay.
Obviously its not the same one as in the auction, but similar and it gets the job done. The one in the auction above looks like it is lit and costs about $36 on ebay.

Edit - Found another similar one at Harbor Freight for $14.99 (then find yourself a 20% off coupon and its $11.99):
http://www.harborfreight.com/seven-way-rv-blade-to-4-wire-flat-adapter-with-flex-cord-67647.html


Another coiled wire adapter is $25:
Hopkins Heavy-Duty Trailer Coiled Wire Adapter for 7-Way to 4-Wire Flat Hopkins Wiring HM47065

Just cut the end off, solder in the wires you need to, cover it with some heatshrink or something and voila!


Obviously it takes time/effort/money to buy a bunch of these parts, stock them, and build them, but that pricing is ridiculous.

Big thanks though to emmado22 for this post/thread.
 
Last edited by a moderator:

Fudge0514

New member
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Location
Oklahoma
I normally don't like to inject confusion into an issue but anyone wanting to use a civy trailer as an example on both their civy trucks and 24 volt military trucks must remember one thing.
Simply changing the bulb from 24 to 12 or 12 to 24 is not the only requirement.
Using the 12 volt industry standard number 1157 bulb as an example;
The bulb is wired so that one filimament is brighter than the other hence the brake & turn being brigher over the other filiament in the same bulb being dimmer for the tail light. When you switch from 12 to 24 volt vehicles and you install the 24 volt equivelant of the 1157 you must also switch wires between brake/turn and tail. If you don't then the brake light will become the dimmer filament and the tail light will become the brighter filiament which is not correct and very unsafe.
The military overcomes this problem by having seperate bulbs for the seperate functions. This way the bulb only has to be switched to the proper voltage depending on the tow vehicles system voltage. The dimmer bulb is always the tail light and the brighter bulb is always the brake & turn as applicable.
The same applies for some of the LED tail lights so you have to be careful of which ones you purchase.
Bottom line is when you are done swapping trailers that have civy lights on them from one system voltage to the other be sure to make sure that the brake / turn is still the brighter set of led lights or brighter filiament and the tail is the dimmer set of lights or filament.
I have seen guys & gals driving down the road with what appears to be their trailer brake lights on all the time and then when they actuate the tow vehicle brakes you generally don't see the brake lights come on which could potentially be a problem for the vehicles behind him or her.
I only bring this up as a safety issue as we all want to be extremely safe while we promote our hobby to others.
Think O.D. Green!

Thought about it for a day or so and I want to calrify what I wrote earlier; If you have an 1157 bulb installed (12 volt) and you put the 24 volt bulb in it's place you have to swap the wires to make the bulb function properly. I do not have experinece with the LED lights but I would imagine that the same problem will exist if you swap from 12 to 24 volt systems.
Hopefully someone with dual votage LEDs will chime in here.

jimm1009
Good info to know.

I plan on making my M101A3 compatible with a civ vehicle 12v system. I have the wiring for the receptable figured out as referenced in my above post. I would like to still use the military lights though. Does anyone know what style light bulb will fit within the military light housing? The dual filament 1157 won't lock into place since the "stumps" are offset in this bulb. The 1156 will fit, but it is single filament. I don't have any more spare bulbs in my tool box so I have to go to the auto parts store anyways.

I might just get the univolt LED tail lights anyways, would just hate to drop $270-ish on lights for a trailer I only use a couple times a year.

In the mean time I'm just running some magnetic trailer lights (which actually work great), can't beat them for $9.99 at Harbor Freight.

Edit - The needed 12v bulbs are the 1156 and the 97 series, and you need a pair of each.
 
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