Ok so i bought an 18 foot car hauler trailer that has electric brakes. I have been doing some research on this site, and have found some answers. I have a few questions too though. Now Im going to go pick up a brake controller and stuff tomorrow, and Im not quite sure all what I need to buy. My truck came with a 4 prong plug at the back, and I know thats easy to change to 7 prong. But im more curious about the whole electric brake part of it. Do I have to run any wires fron the front to the back of my truck or is most of that stuff there from the factory? Thanks for any replies!

 

Depends on the year, but all the newer trucks (1999 and on, maybe older) are wired for the brake controller. What the tow package adds is the 7 prong harness. If you trace the 4 pin plug back up into the frame you will find a large plug. On the other end of that plug you will find some dead-end wires, one of which is the brake wire. If you go to the store and buy a seven prong plug, tap into the 4 pin for the normal lights, and run a wire from the brake wire at the harness plug back to the 7-pin adapter. It's only a foot or two, very short.

That's all the wiring you need to do, at least outside of the cab. The inside stuff is easy. Go to Uhaul and pick up a brake controller, at LEAST the Voyager. Don't get anything cheaper than that. There are two versions of the Voyager, one for two axles, one for four. Next look around for the adapter wire for your truck. Did you get a little pigtail with the truck, usually in the glove compartment? If not, pick one up at the Uhaul dealer, they only cost a few dollars. Read the directions of both parts and wire them together. Mount the brake controller somewhere on the dashboard and plug the pigtail under the dash. There is only one plug that will fit, its just to the right of center under the steering wheel, just behind the kickplate, next to the diagnostic plug in. Again, there is only one plug that will fit. Tie up any extra wire and you are done! Use the directions to tune the brake, out of the box it won't work correctly. It needs to be adjusted carefully. I made it sound more complicated than it is, it will only take you 15 minutes from start to finish to do it all

 

I just bought a Voyager, it's pretty slick, and comes with a dvd to watch!!!

 

If im corect ther are also two relays that need to be added the the fuse box under the hood. My 02 came with the pig tail that you are talking about as well as the two relays

 

You don't HAVE to put in those relays, plus if you follow the directions I posted the relays won't do you any good Those relays are for the other two wires that end at that junction near the spare tire, the aux power wire and one other (backup lights?). All you need, unless you have a travel camper, are the four pin wires (right, left, running, and ground) and the electric brake. Some trailers, but not all, use the aux power to charge the breakaway system, but you can get away with just keeping the battery fresh and checking it from time to time to make sure its still good. Finding those other wires is a little more difficult and I don't recall exactly how to make them wire in correctly.

 

So the six pin would have right, left, running, ground, brake, and aux, whereas the seven pin has all of those plus reverse lights. All you NEED is the five I mentioned before unless your specific trailer requires more. A carhauler, most horse trailers, etc 5 is all that are used.

 

i did about waht Graf said. mo 2001 SC was setup with a 4 pin arrangement. I bought the Voyager and mounted under the dash below the steering wheel. plug into the connector in that area.---- the 4 prong plug goes up to the left frame rail by the spare tire and plugs into a big round connector with several wires. i jumpered the big brake wire around the plug and put a new 6 pin connector on the back for the car trailer. you dont need the relays without backup lights and battery on the trailer. works great.

 

Thanks guys, it was extremly easy to get to work. All I had to do was get a controller that plugged in under my dash. I plugged it in, found one wire underneath the truck, ripped out the four prong and installed the 7 prong, added the blue wire I had to find under the truck for the trailer brakes and I was good to go! I had that fuse under the hood for brakes, and I didnt need to add any relays or anything, so its possible my truck had them in it before.

 

My truck came with tow package and has the Aux power at back for battery charge and back up lights. I think I found the pig tail you guys are talking about. Is it the gray plug to the right of the Data link connection?

 

I think so... there is only one plug that will fit it. The pigtail usually is in your glove compartment, the corresponding plug for the pigtail is right next to the diagnostic connection.

 

I've seen the plug under the dash, but there is no pigtail connector in the glove compartment. I bought the truck used.