I have a 2000 F150 5.4L without the towing package. I'm trying to connect my brake controller and I couldn't find anywhere that had the plug and play wire harness so I had to splice into the harness under the dash.

Here's the problem I think i might have spliced into the wrong harness. The brake controller turns on and functions fine, but I don't know which wire controlls the electric brakes.

The harness i spliced into is directly next to the diagnostic port, it's got a six prong set up with 5 spots in use. The wires are white, black, red, light green, and blue. I figured the blue was the electric brake wire but it's not.

I've hard fed a wire from the flat 5 connection in the back all the way into the dash and the manuel slide on the brake controller stops the trailer tires, but the brake pedal does nothing.

So I need to know where the electric brake wire is. I know I have a fuse in the fuse box for the electric brakes so I figure that must a wire hanging around somewhere that I just need to splice into.

Please help. TIA.

 

Any trailer dealer or trailer repair shop will have the correct wiring harness as well as most auto parts stores. Slicing into the factory harness is a great way to end up with a wiring short.

Here ya go for the truck:
White--Ground
Red--12v positive
Black---actually brown----dash illumination
Light Green--Brake light switch
Blue--Trailer Brake Feed

EDIT:
For the brake controller: (I'm sure it's on the package too)
White---Ground
Black---12v positive
Red--Brake light switch
Blue--Trailer Brake Feed

Um...if you are looking at the grey connector directly above the OBDII port, yeah.. the blue is the electric brake feed.

Does the brake controller light up when you press the truck's brake pedal? If not you need to connect the light green wire to the brake controller's red wire, because it sounds like the truck is not telling the brake controller to turn on.

Good luck...let us know how it turns out.

Why are you using a flat 5 connector....the standard in the industry since 1997 is the 7 round RV style connector. Most new trucks and trailers now use this connector....with the exception of small non-braking trailers using the flat 4 connector.

 

Thank you for your info. It all helped. I just had it wired incorrectly. I attached the green wire and removed the black/brown wire from the red one and everything works now. Thanks again. One more thing though. The wire that runs the lenght of the truck is 16 guage. Is that enough or will the current eat that up? It also feeds right into the splice between the brake controll connector and the truck connection(right where I spliced the wires together). Is this improper? It's the only place I could find the Electric brake wire to tap into it.

 

There is a wire that goes goes from the under dash connector to the rear bumper. It will be in a bundle that the other trailer light harness is plugged into. Some years of these trucks had 2 bundles...one for lighting and another for aux power and brakes....so it is either with the wires back there next to the spare or right next to it.

16g is plenty......Ford runs 12g for brake wire, but Dodge and Chevy run 18g.

 

This shows some of the wiring.

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