Trailer: 4 pin & 7 pin wiring question

[Mantooth]

Recently bought a 3.5K aluminum trailer to use when I need to haul my SxS or zero turn mower with the Durango listed in my sig. This will be used when the F250 is being driven by the wife for hauling my daughter to-and-from her horse show practices/competitions.

I'm wanting to add electric drum trailer brakes on the 3.5k trailer. My Durango has a tow package so it already has a factory 4 pin & 7 pin plug. The trailer currently has a 4 pin connector that I am wanting to retain in addition to adding a 7 pin to accommodate the brakes. I've looked around and a 7 pin to 4 pin reducer doesn't seem to exist for obvious reasons.

The place I am planning to order my brake set-up from told me I couldn't do this but didn't explain why - my plan is to get a junction box and wire both connectors to the box. I'll use the 7 pin connector for vehicles with proper plug and the 4 pin for vehicles that don't. Obviously, the 4-pin wires won't be connected to any brakes leads and vice versus. My thoughts are the online place said I couldn't do it for liability reasons. My question is there a technical reason why having two connectors would not work? Would having two plugs create an electrical issue?

I'm sure someone will ask why I want two connectors - the reason is that I have several friends who will end up borrowing this trailer to haul lawnmowers, etc., and won't have 7 pin hookups on their vehicles. This way they can use it and still have the appropriate lighting. I want brakes for when I tow my SxS in the Ky and WV mountains.

Thanks in advance.

 

[exranger06]

No, there are no reasons why that wouldn't work. From a technical standpoint, it'll work perfectly fine. I have no idea about the liability aspect.

 

[meep]

I'd convert the trailer to the 7 and not include the 4.

1. the four pin will leave (+) exposed when the 7 pin is in use, creating the potential to short.

2. if you were carrying a load needing brakes, but someone borrowing the trailer just used the 4-pin, the brakes won't be available. Whoops.

3. 7 pin is a more substantial physical connector.

4. the liability thing is real to the shop. I modified factory wiring in a tow vehicle and they wouldn't sign off on it for the trailer inspection. They are required to go "by the book" for all systems involved in vehicle safety.

OTOH, brakes aren't required until you reach 3500 lbs, which is the max load of the trailer. Does it need them? A durango won't sweat nothin' with an aluminum trailer and a riding mower. Brakes, unless set waaay down, will have a tendency to lock with the trailer empty, and possibly even with the mower.

 

[bullwinkle]

Trailer brakes are REQUIRED on ALL trailers in WV, over 2000 lbs. here in OH, over 3000 in IN. KY doesn't specifically require them, but they're always a good idea. The best solution is a 7 pin on the trailer, with trailer brakes connected-pretty much any vehicle that has a factory trailer towing package has a 7 pin socket. If I was to put a 4 pin on it, I would solder & heat shrink an extra 4 pin harness on the trailer, hooking up the ground & lighting wires to the 7 pin that was already on it.

 

[meep]

Originally Posted by bullwinkle
Trailer brakes are REQUIRED on ALL trailers in WV, over 2000 lbs. here in OH, over 3000 in IN. KY doesn't specifically require them, but they're always a good idea. The best solution is a 7 pin on the trailer, with trailer brakes connected-pretty much any vehicle that has a factory trailer towing package has a 7 pin socket. If I was to put a 4 pin on it, I would solder & heat shrink an extra 4 pin harness on the trailer, hooking up the ground & lighting wires to the 7 pin that was already on it.


^^^ good points. didn't know the requirement for trailer brakes varied per state.

 

[mk378]

When a trailer has brakes, they have to be hooked up, or it's a liability. Anyone seeking to borrow your trailer needs to have the proper equipment on their truck.

 

[SwampSurvivor]

I'm in the process of a car trailer right now. They are like trucks, when you have one, someone will need to borrow it. For that reason, I'm realllllly going to try to get the surge brakes working. Then the wiring can be the standard 4 pin --- which should work fine for the requirements in NY, Uhaul trailers use is --- and still have functional brakes.

I know a lot of people who do tow vehicles on a trailer with no brakes. Either the trailer doesn't have functional brakes or their truck doesn't have a brake controller. I'd feel better knowing that they have brakes.


I wouldn't recommend using the 4 pin to control the electric brakes. First - there may not be enough power coming out of the 4 pin. Second, it's not going to be able to variably control the brakes - it's going to be an all or nothing. Trailer brake controllers can change the amount of brake applied.

 

[Rand]

I would not add brakes its not required by your state, adds additional maintence and expense.

and need to be adjusted to your load.

Your load doesnt seem to be much for either of those tow vehicles and meets your state law.

Now if it was a 5000lb boat or some a travel trailer then yes brakes
both because its a heavier weight and a more constant weight

 

[Mantooth]

Just to re-clarify some of the points in my post. I'm not looking to use a 4-pin plug with the brakes. The 4 pin wires will only be connected to the appropriate lights via the junction box. The 7 pin plug will operate lights and brakes for any vehicle with a 7 pin connector.

My state, Indiana, does not require brakes on all trailers. This trailer has a 3.5k axle and therefore brakes are not mandated. I mentioned using it to haul a ZTR mower because it will occasionally be used for that type of machinery. The reason I am looking to add brakes is because of my 1,750lb Honda SxS that will be on it. There is also the chance it will have a 490lb Honda ATV on there as well. Those two things, plus the weight of the trailer, will put it at just under 3k. I'm just wanting to add a little extra braking for those times I am towing in the Eastern Kentucky or West Virginia mountains. No use in heating up brakes and rotors if I don't have to.

Someone mentioned having two plugs would not cause a wiring issue...so I will probably put this on my to-do list for the summer. And to address the fella who pointed out that I would have an exposed plug while traveling, each plug will have an end-cap. That way, whichever plug is not in use will not be exposed.

Thanks for the suggestions.