My 89 f250 has the factory tow package with the seven pin plug. I have found the blue/black stripe (early ford color?) and have it wired to the brake control (pin 2) but cannot find where it would hook to a controller under the dash. There is a white box (right of steering column) with a black box two plugs twelve wires beside it. Can someone help figure this out?

 

I'm pretty sure a brake controller will have a lever for manual activation, accessible from the driver's seat and tie into the brake light switch somehow.
All the controllers I've seen have 4 wires - ground, power, brake light input and trailer brake out.
If you don't have a controller, well, that might be needed.

I think the black box you are talking about is the cruise control module.

 

The truck doesn't have a controller (yet) but I wanted to sort out the wiring brfore I make the purchase. I found the bl/blk under the hood going to a relay but didn't see it under the dash so was not sure where I should tie the controller into it at.

 

Look by the e brake there is a round connector over there,. Good luck fining a ford controller. To use an aftermarket controller you are going have to splice wires

 

i had 6 of these trucks with factory tow package, and none of them had factory trailer controllers in them. they had the plug in the back, but i had to wire in the controller in the cab.

 

Should be a 3 pin plug under the carpet/ vinyl flooring, my 89 has it.

 

When you wrote '...seven pin plug' did you mean 7-way flat blades style which is an RV style which also works with a lot of non-RV trailers (utility, car trailers etc.) or do you mean round pin connectors(?) which I recall are for large heavy duty work trailers and the plugs are wired differently. Chances are, your truck has the former.

I am in the process of figuring this out myself for my 87. It has a Tekonsha Voyager controller already wired in but the 7 way plug was removed so I have to wire in the new 7-Way connector (plug). I just have to trace the wiring from the controller to see how it was originally wired in before I can proceed. I can't do that today due to a sore lower back.

Bottom line is that you have to follow the controller instructions to start with and figure out where to connect each wire based on identifying the appropriate wire in your truck. I can post the schematic to show those later.

There is also a RELAY in this tow package circuit and I don't know where that is located yet. Also a 20 amp cartridge fuse in a black wire associated with the tow harness on the driver's side.

I have the wiring diagrams for all plus the factory tow package harness schematics from the 1987 shop manuals which will be the same as your truck but how the manuals show the brake controller being wired in (wire colors and number of wires etc.) is not the same as the more modern e-brake controllers so you'll have to go by the instructions that come with the controller combined with the schematic of the wiring in your truck.

I can't deal with that right now - until after I get some sleep.


In the mean time you can find all of this information but in a "not- specific to your truck" form at etrailer.com. You should go there and have a look.

IF you buy the same makes and models of controllers that they sell there, like the Voyager or P-3 you can post a very specific question as to how to wire that controller to your specific truck and you'll probably bet a very precise answer. They have replied to others with questions about wiring in a very specific make model and year of truck.

STILL I think you need to have the generic knowledge about how it all works AND confirm every wire's function at the 7-way connector with a test light or meter to make sure it was connected properly.

 

Ok a little follow up here. I was able to get the seven pin (RV Blade Type) tied to the factory tow package harness and hook up the controller to the factory harness and pull a 33ft travel trailer a couple hundred miles this week. The rear harness which consist of two plugs was fairly straight forward. One plug has the standard four pin wiring (blinkers, brakes, backup, and running) lights. The other plug has four wires also which stumped me for awhile. I was able to figure out it was old Ford colors and hook three up (12v, trailer brake, ground) but could fire out the fourth a red with lightt green stripe I think. It turns out that fourth is trailer brake lights with manual controller. In other words when you manually engage the trailer brakes through the controller the brake lights will come on like you pressed the brake pedal. I found the plug for the controller under the carpet by the E brake pedal and spliced into it (which I didn't want to do but noone has the factory plug) and hooked up an after market controller right there.