trailer brake wires

[shaper]

12 years ago I put brakes on the front axle of my 16 ft. utility trailer. A couple weeks ago I decided to put new shoes on the front wheels and install brakes on the rear axle also. Installing the new brakes and hubs were no problem. Then time came to run the wires at all four points. That is when everything went down hill. As a general rule I don't touch anything with wires on it. Mainly because I just don't know what I am doing. I have been working on the wires on this trailer for two weeks now and still don't have working brakes on either wheel. Went on line and found a wire diagram. There was a picture of the plug with 7 positions for the wires. But there is a inner wiring location and a outer wiring location. What gives with that, which do I use?

[flyingmonkey35]

Attachment of wiring diagram will help + photos. If you can.

[bdicki]

http://www.cumminsforum.com/forum/attachments/towing-hauling/12103d1229058428-rewiring-7-pin-connector-wire-colors-7waytrailerend.jpg

[Tackleberry41]

The wiring itself should be pretty easy, all 4 brakes on the same colored wire running back to the plug. When I worked at a trailer place, we used a battery charger to test the circuits. Neg clamped to the frame of the trailer, a probe of some kind to stick in each hole in the plug. Full power the brakes should lock. Biggest issue was generally the abuse wiring takes hanging under a trailer, its seldom strapped down, so breaks, may not see it. The other issue was generally the ground, come loose, corrosion, etc. Bad ground nothing works or doesn't work well or intermittent.

Easy way to test the brakes is without the the plug, hook up your charger to the hot lead going to the brakes.

The inner and outer is just having enough room for everything. Standard plug is 4 prong: running lights, brake lights, left, right turn signals. Brakes requires the round plug to have enough prongs. Some are not used, unless providing 12v power to charge a battery etc.

Theres also the power provided to the brakes from the controller to deal with. Make sure that works.

[lancem]

http://www.etrailer.com/static/images/pics/q/u/qu6825_800.jpgInside means l looking at the plug from the "inside", outside looking at it from the outside. When hooking up your new brakes all you needed to do was parallel the wires from the brakes on the front axle.

[woody1]

Inner/outer = outside is what you see after wiring is complete and you're looking at the unplugged connector.
inside is where you put the wires = inside the connector/where the wires go.

I hate trailer wiring! I shouldn't assume anything, but you do have a test light don't you?
Who did the initial wiring of the vehicle and trailer? Was it wired to any standard? Have you checked the trailer ground?

For the future.....put a copy of the trailer wiring diagram in the vehicle or some place you can find it later (like now.)

Regards, Woody

Guess I was typin' while y'all were sending. Yeah, what they said!

[shaper]

the blue wire from the controller is located in the center of the female plug on the truck. The controller and wires were added to the truck before I bought it 16 years ago. I added grounds to the frame near the wheels.
The reason I am replacing all of the wires and plugs is water got into the male plug, it froze and cracked the case. everything inside rusted and can't be used again.

[imashooter2]

You need a ground all the way back to the battery, not just to the trailer frame. That's where I'd place my bet.

[DougGuy]

You should take a 12v test lamp and make sure the plug on your tow vehicle is the same as how you intend to wire the trailer plug. That could be half your battle. If it is wired differently, you will have blown fuses in the tow vehicle, so check all the functions on the tow vehicle and make you a drawing of which terminal does which function.

Start the vehicle and turn on one of the turn signals, then go back to the connector and find which terminal is blinking your tester, same with the turn signal on the other side. Pull your lights on and see which terminal has a steady 12v on it, this will be your running lights (not to be confused with marker lights) this should illuminate the smaller filament in the trailer's taillight bulbs, AND an orange side marker light near the front of the trailer. Have someone sit in the tow vehicle and depress the brake pedal, this terminal should connect to the larger brighter filament in the trailer's taillight bulbs. Now have them operate the lever on the brake controller, this should send a varying signal to the terminal that goes to the trailer brake solenoids, your tester should be getting bright then dim then bright then dim as they work the controller.

Make SURE you have a ground wire from the trailer's frame, to the connector, and on the truck side of the connector either to the truck's frame or all the way to the battery. Don't just assume it will ground through the ball coupler. Most will, and many do, but this is an iffy way to do it and may only work some of the time.

Hope this, along with the drawings above, help.

[leadman]

Are you using the 7 wire plug? You never did state that you are using the 7 wire plug. There are a couple of other choices to run lights and brakes thru a plug connection.
Grounds are the biggest problem with wiring on trailers so I always run ground wires to the brakes and battery from the tow vehicle.

[Idz]

Drum type electric trailer brakes can be tricky. If the actuating levers are backwards or they are not adjusted correctly the electromagnets can work fine but you'll get no braking. You can usually hear a clunk if you actuate the brake magnets so you'll know if they are working. The magnets don't provide the braking, they pull a lever against the drum which then uses the rotating force of the drum to lever the brake pads into action.

[Reg]

Something else to keep in mind.

Check ( look in the owners manual ) the fuses on your PU. Many pickups actually use a second set of fuses for the trailer wiring.
The turn signals, etc, on the truck might work fine but not on the trailer, look for that second set of fuses and check for blown fuse.

Ran into this last week when redoing a bit of wiring on a 16 foot trailer I had cut down from a 20 foot. Could not get the LH turn signal to work. It did work on the prior PU I had ( a 96 ) . Looked in the book, found that second set , checked the LH turn fuse and sure enough it was blown. Replaced it and all worked fine.

imashooter2 and DougGuy are both right. Make sure your ground is clean and positive. A full wire from the battery is a good idea. From working in trailers for over 30 years a bad ground on a used unit is most often the culprit.

[GaryN]

What I hate is after all the work wiring it you wait a year and all the wiring is going bad. I have been having trouble even finding good wiring. Everything is from China. Where do you go to buy decent wiring setups?

[Minerat]

Another thing I ran into is that you need to connect the back brakes to the front brakes (in series??) on both sides and run one wire to the junction box. There's a junction box between the axials on both sides that the wires from each brake goes into, it then splice in to a single wire and to the a junction box on the front of the trailer and then the Right & Left spice to a single wire that goes to the plug. I have a wabbit or mouse that likes to chew the wires between the axials and then neither set will work. I finally ran the exposed wires between the brakes in a piece of conduit. GROUND GROUND GROUND On the trailer I have, the ground corrodes then they won't work. On mine if the lights are dim then the ground is bad.

[David2011]

I'm just going to offer my sympathy. I went through this last October with a trailer I bought to put on the hunting lease. My 2000 F-150 Ford truck had the connector in post 5 when I bought it. The trailer had the connector in post 3 but it was damaged. I had to remove the trailer connector and replace both with the style in post 3. Predictably, the truck's wiring colors were industry standard but the trailer's were not. Lots of fun to figure out. I used my R/C airplane starter battery to power the trailer wiring and identify which wire did what. The motorcycle battery and a test light made it much easier.

David

[Mk42gunner]

A few things I have learned while working on older trailers:
1. Make the trailer conform to industry standards; this way you can pull the trailer with any pickup or SUV with a standard connection.
2. New wiring solves most problems.
3. Soldered connections covered with heat shrink tubing lasts better than twisted and taped.
4. Plastic conduit does wonders for protecting trailer wiring.
5. Electric trailer brakes are a PITA to work on, but they are worth it when you really need to stop right now.

I do not like surge brakes, most of the ones I have pulled seem to quit working when they are a few years old because the push rod corrodes and gets sticky.

Robert