Pulling civy gooseneck with M931

wreckerman893 · Mar 17, 2012

Since I have a fondness for M915's and other military tractors I have bought an adaptor that will allow me to pull my 28 foot civilian gooseneck trailer with a road tractor.

I can fab up an adaptor to use a 24 volt plug (on M818, M931, M275, etc) to run a set of auxillary brake lights/turn sigs/running lights (or borrow a set of tow lights).

What I need is a way to make the electric brakes on the trailer work.

Any ideas from the faithful????

DieselBob · Mar 17, 2012

wreckerman893 said:
What I need is a way to make the electric brakes on the trailer work.

Any ideas from the faithful????

Couldn't you just use a standard electric brake controller ?

DieselBob · Mar 17, 2012

Found one..http://www.southwestwheel.com/store/p-45-hayes-airelectric-brake-controller.aspx

wreckerman893 · Mar 17, 2012

Man........you're good.

Thanks much.

Derrickl112 · Jul 7, 2012

I have been searching for about an hour now without much luck. There are many threads on this subject, but I can't find anything that shows step by step how to add a civy 7 way trailer plug AND an electric trailer brake controller to a 24v 5 ton/deuce. I do not want to modify my trailers in any way.

Help?!

Csm Davis · Jul 7, 2012

There is a 24 volt to 12v light converter on some military trucks, I have one for mine but they are expensive around, $500 and it uses a semi style output plug not sure how you would wire the trailer brakes in to that.

goldneagle · Jul 8, 2012

wreckerman893 said:
Since I have a fondness for M915's and other military tractors I have bought an adaptor that will allow me to pull my 28 foot civilian gooseneck trailer with a road tractor.

I can fab up an adaptor to use a 24 volt plug (on M818, M931, M275, etc) to run a set of auxillary brake lights/turn sigs/running lights (or borrow a set of tow lights).

What I need is a way to make the electric brakes on the trailer work.

Any ideas from the faithful????

The cheapest way is to install a 12 volt actuator ($56.00) and use a relay off the brake switch to activate the controller. You run the wire from the brake switch to the coil of the relay and tap a 12volt line on the switch side. When the brake peddle is depressed the 24 volt triggers the relay and allows 12 volts to go to the actuator.

I bought the relay and harness for $14 delivered off Ebay. I'm doing that in my Deuce so I can pull my car hauler in back of it.

RangerBob · Jul 8, 2012

Lots of threads on the 24V-12V trailer lights and brakes thing, but here's my try at it...

The electric brakes should be a done deal with this MaxBrake. $350 for hydraulic, $390 for air.

Lighting, which should be the easiest, seems to be the hardest to solve (cheaply). The SEC box will do it, but for $500-650, and you still need a cable!! :doh:

Maybe this Aussie box will do the trick. I think it goes for about $200.

So I'd stick a 7-way civvy connector next to the mil connector, tap and splice the wires from the mil connector, through the Aussie adapter, and over to the civvy 7-way connector. Then connect the output from the MaxBrake unit to the 7-way. Done.

wreckerman893 · Jul 8, 2012

Since I sold my M915 this project has been on hold (although I do have the kingpin adaptor already).

Since I have a set of military tow lights I'll use them rather than fabbing something.

I'll still need the adaptor to make the electric brakes on the trailer work.

goldneagle · Jul 8, 2012

RangerBob said:
Lots of threads on the 24V-12V trailer lights and brakes thing, but here's my try at it...

The electric brakes should be a done deal with this MaxBrake. $350 for hydraulic, $390 for air.

Lighting, which should be the easiest, seems to be the hardest to solve (cheaply). The SEC box will do it, but for $500-650, and you still need a cable!! Maybe this Aussie box will do the trick. I think it goes for about $200.

So I'd stick a 7-way civvy connector next to the mil connector, tap and splice the wires from the mil connector, through the Aussie adapter, and over to the civvy 7-way connector. Then connect the output from the MaxBrake unit to the 7-way. Done.

Do you work for the GSA or other government agency? You seem to prefer the most expensive solution to the problem! :roll:

RangerBob · Jul 8, 2012

goldneagle said:
Do you work for the GSA or other government agency? You seem to prefer the most expensive solution to the problem!

Yeah, that controller is a bit pricey compared to standard electric controllers, but more versatile and sensitive/proportional. Works for air or hydraulic. Looks to me like your solution is a binary braking solution (trailer brakes completely on or off), true? If so, yup, that's cheaper.

Maybe I misread and you were just explaining how to get 12v to the real brake controller on demand rather than fulltime.

goldneagle · Jul 8, 2012

RangerBob said:
Yeah, that controller is a bit pricey compared to standard electric controllers, but more versatile and sensitive/proportional. Works for air or hydraulic. Looks to me like your solution is a binary braking solution (trailer brakes completely on or off), true? If so, yup, that's cheaper.

Maybe I misread and you were just explaining how to get 12v to the real brake controller on demand rather than fulltime.

The controller has settings that can be adjusted for timing and the amount of braking pressure. I used to have the Draw-Tite Controller in my Isuzu NPR and I was able to adjust brake pressure with the dial on the controller. It was wired to my brake light switch. I believe the brake switch is on/off not variable. The controller has a separate 12 volt feed from the battery that actually activates the magnets on the brakes. Much heavier wire than the one from the brake switch. (I think it requires a 30 amp auto reset breaker)

tm america · Jul 8, 2012

Correct me if i am wrong but didnt the 900 series trucks come with a 12 volt system on them?I thought they had a dual voltage alt or converter on them...If so all you would need is a standard brake controller

ARYankee · Jul 8, 2012

tm america said:
Correct me if i am wrong but didnt the 900 series trucks come with a 12 volt system on them?I thought they had a dual voltage alt or converter on them...If so all you would need is a standard brake controller

Yeah there is a 12 volt tap for the heater. Someone posted that in another thread and I verified it with that really cool P2P program for the 900 series trucks.

Csm Davis · Jul 8, 2012

ARYankee said:
Yeah there is a 12 volt tap for the heater. Someone posted that in another thread and I verified it with that really cool P2P program for the 900 series trucks.

939series ? Or not sure what the series is but 915-920? Which one are you referring to? The 939 series has a 12v hookup on the batteries but 24v only alternator.

Csm Davis · Jul 8, 2012

Wreckerman here is the easy cheap way Installing Electric Brake Controls on 24 Volt Vehicles | etrailer.com

Csm Davis · Jul 8, 2012

Here is the wiring from that site in case it goes away.

Stonepicker1 · Jul 8, 2012

Csm Davis said:
Here is the wiring from that site in case it goes away.

The issue:
NOTE: The trailer brakes will operate on 12 volts. The trailer lighting will remain at 24 volts.

Csm Davis · Jul 8, 2012

If you really don't want to have any loose wires or extra connections you could run it through the trailer plug there are some unused pins on the truck and it could go out the normal trailer brake pin on the civilian plug.

Csm Davis · Jul 8, 2012

Stonepicker I have that covered in a couple different ways and I an looking at building some converter boxes for this. :driver:

Pulling civy gooseneck with M931

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