Expedition 6 or 7 pin trailer wiring - help please

Trying to wire up my Expedition for a trailer brake control. Bought an 7 pin RV style plug with adapter that plugs into the 4 pin standard harness. It has 3 wires left that need hooked up (white which I assume is ground, blue which I think is the brake control and yellow which I have no idea).

Question is, in the 4pin standard Ford wiring harness, there's another plug in the same harness with two more wires (blue & red); are these for the brakes on the trailer? If so, two questions:

  1. Where does the blue wire go and where does the red wire go?
  2. Do I even need an add on power brake control for the electric trailer brakes?

Thanks, sorry in advance for my ignorance on this subject.

Todd West

Reply to
Todd
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Well if you don't hook a wire up to the brakes, the brakes on the trailer will not work. Put a meter on them and see when voltage comes on. My 7th wire is for backup lights. Some are 12 V for charging the battery on the trailer. So it depends!

Reply to
dewatkins

I suggest you take that adapter back and get down to the Ford Parts dept. Get the wiring harness for the tow package and the brake controller pigtail. For my 98SC they were about $80. The wiring will replace the 4 pin one. Depending on your model year, you may find that the 12V aux relays have been factory installed. If not you will need to get those too, in order to get the 12 V aux pin powered up.

Yes, you will need a brake controller. I suggest the Jordan Ultima 2020, has a cable that runs to the brake lever. Only one control on it, max output. I believe their website is

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Others might recommend the Teskona(?) prodigy.

Reply to
William L. Toth

Prodigy is easier to install, works wonderfully and has a much larger company behind it.

Reply to
Chris Hill

A new Expedition or F-150 will come with a wiring diagram in the owners manual if equipped with the factory tow package - maybe you could borrow a copy from a Ford dealer to photocopy. My new F-150 came with the diagram, and with the wiring harness that plugs into a matching receptacle up under the dash. All you need to do is get a brake controller, the harness for under the dash, the harness for the rear of the truck, and solder up the wires according to your controller diagram and the Ford diagram and you'll be off to the races. Don't use those crappy crimp connectors on a brake controller. Sooner or later they come loose from vibration, and the brakes on the trailer will quit working when you least expect. Solder the ones at the back especially and use heat shrink tubing so the water and salt doesn't get in to the connections and you'll have zero grief.

The other user is right about the relays and fuses and and auto reset breakers. You'll need several of them if your truck didn't come with the tow package. The owners manual will show you the locations and the sizes to buy. It's been three years since I installed my relays, but if I remember right, most of them are in the flip fuse box on the drivers side under the hood and I think there are about 6 in total for towing.

The trailer brake wire (blue I think) will vary from 0-2 volts depending on what your controller sends it. The other wire (red I think, is hot only when the engine is running and a relay closes - it comes from the alternator to charge the trailer batteries. Make sure you've got the 100 or 130 amp alternator. The 60 amp one might get bagged out if your trailer has lots of lights. Make sure your vehicle battery is strong before you tow anything heavy. If your motor quits for any reason, the vehicle battery is the only thing that's gonna stop you.

I think the other guy is right - the 7th wire is for back up lights, or for any other use that you deem fit.

I put a Hayes Lemmerz Synchronizer on my truck and I'm not impressed. There is too much lag after I hit the brakes in the truck. I'll check out the Prodigy. Thanks for the recommendation.

Hutchmeister Canadian Eh.

Reply to
George Hutchison

Thanks for the excellent info.

Reply to
Todd

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