Trailer brake questions

I have a car trailer with the rear axles having brakes. It is old enough there is no breakaway system.

First question, can I/should I install a break away system?

Second question. My first pickup I used an adapter to go from trailer 6 pin round to the truck 7 pin. Both before and after adding a brake controller, I never had brakes. Lights worked fine, controller showed a trailer and braking, but no brakes. Tried the trailer on two different trucks (one with, one without a controller) and the brakes lock up as soon as you touch the brakes and will not release until the trailer is unplugged. I no longer have the first truck, so I dont even need to troubleshoot that issue. What I need to figure out now is why they lock up and will not release. I was tempted to mount an electrical box on the tongue and splice in a new lead to the truck. Should I stick with the 6 pin or move directly to the 7 pin?
 
I'd hazard a guess that there are wires swapped somewhere... the fact the brakes locked on on the one truck and wouldn't release means they were working, and probably getting power from the live 12 volt supply. Seeing as there seems to be no standard wiring colours for trailers, you will probably need a test light and lots of patience, as somewhere there is a connection made wrong. Start by checking the truck plug, it's possible the track has a separate fuse for the trailer system, so make sure all the fuses are ok, then work your way through the trailer checking for power to the appropriate wire.
 
I would definitely install a break away system. I think its required anyways and it doesnt matter how old the trailer is, and that requirement may vary by state.

It sounds like someone wired something wrong. Its actually difficult to screw up the trailer wiring with the exception of the plug. Could have a couple wires going to the wrong pin.
I just put new brakes on my trailer last summer. The wiring of the brakes themselves is easy.
 
i assume the breakaway can be fitted to any trailer regardless if it was originally not installed? Going with that idea, do I need to go with the 7 pin plug then?
 
I have found blown fuses for the trailer wiring. Also which truck would lock up? I'm assuming the one without the controller, all trucks I've ever seen without controllers pulling trailers with brakes will lock them up... that's one reason for a controller. Also something is probably wired wrong, If you have a dodge research the mods for trailer plugs, I had to switch a couple wires on my adapter for correct function.
 
locked up with two different new Chevys. One with, one without a controller. I will start into the wiring this weekend. Seeing the pigtail definately has been rewired a some point.
 
(quoted from post at 14:20:41 04/07/15) I'd hazard a guess that there are wires swapped somewhere... the fact the brakes locked on on the one truck and wouldn't release means they were working, and probably getting power from the live 12 volt supply. Seeing as there seems to be no standard wiring colours for trailers, you will probably need a test light and lots of patience, as somewhere there is a connection made wrong. Start by checking the truck plug, it's possible the track has a separate fuse for the trailer system, so make sure all the fuses are ok, then work your way through the trailer checking for power to the appropriate wire.


It does sound lkke wires are crossed. I would install brakes, 4 way is better but they need to be the same as the existing ones. I bough new 4 loaded backing plates and 4 drums with bearings on my 7000 LBS trailer for under $400 from Etrailer.

There is a standard, it would be nice if everyone used it.
http://www.rvupgradestore.com/v/vspfiles/assets/images/1wiring.jpg

1wiring.jpg
 
Your brake wire and 12v positive are switched between your vehicle and
trailer. So when you plug the trailer in, the brakes are constantly getting
12v and locking up. With no breakaway system in the trailer, you won't have a
wire for 12v power....that's what would be run to the breakaway battery to
keep it charged. Open up your trailer plug and switch those two wires and all
will be fine.
 
I had a chance to look at it this weekend and it does look like those two wires were switched. After looking at it and seeing the several wire splices, I have decided to yank it all off and start over with a junction box. Make it much cleaner and easier to troubleshoot. I am also going to add a break away brake system.

I have a question. Rather that putting back a male pigtail (and not being able to decide what plug to use), I am debating on just putting a 7 pin female plug on the trailer. Then I will get 4' male to male cables, making them either 7 to 7, or 7 to 6 pin as needed. My thoughts are when the trailer is sitting unused, there will be no wire hanging. Anyone else ever do that?
 
Former father-in-law set up his boat trailer with a removeable jumper cable. Just another set of
contacts to corrode while sitting, & usually forgot where he stashed it "where he wouldn't lose
it".
WJ
 
(quoted from post at 10:22:52 04/13/15) Former father-in-law set up his boat trailer with a removeable jumper cable. Just another set of
contacts to corrode while sitting, & usually forgot where he stashed it "where he wouldn't lose
it".
WJ

That is an interesting perspective. I guess I thought on the trailer having a covered female port would be less corrosion than a
male plug hanging there. And having the "exposed" male plugs under the back seat in the truck would be the best place to store it. Something to think about I guess...
 
If your talking about doing a setup like a tractor trailer, sure, it will work fine. I did it on my old trailer a few years ago, in fact my trailer female came from a trailer we scraped at work. Guy who bought it loved it, and is still using it like it is. At work, we use a little dielectric grease on the plug ends, and the trailer ends when the trailers get serviced.
 
The 7th pin is generally not even used. It's for reverse lights, and most trailers don't have those.

You are feeding straight 12V from the battery charging circuit to the brakes.

Breakaway systems are simple to install. They come with instructions.
 
Finished this up today. Before I started testing, I just starting ripping. The wiring had been spliced a couple times, so I just started over. I installed a junction box on the tongue to make it easier to test and change things. Its a good thing too. I had everything wired and tested ok all the way to the end of the plug...but when I tested it was still wrong. Got to looking at the 7 to 6 pin adapter and sure enough, printed right on the dumb thing, it said center pin brake. Flipped it over and it said to open here to swap wires. Opened it up and inside the two wires (brake & power) were the only two not soldered, just screwed in. I swapped those and everything works great. In the end, all I really had to do was swap that wiring in the adaptor. But I really like the cleaned up look. Added a junction box, new plug, and a break away system.
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