What is this plug in for?

[foresterdj]

Was cleaning up some of the previous owners cobbled up wiring under the truck today, and also continued searching for where the short is in the electric lock wiring. During the process, noticed this plug-in, which seems to be a factory set up. It was unplugged, no other wire nearby to plug into it, and PO had a wire tie cinched around it.

Anyone know right off what this is for? It comes through the firewall near the left panel behind the E-brake. If not, I'll just need to trace it to its terminus at a later date.

 

[Drew2010]

brake wiring for a brake controller.

 

[94f450sd]

kinda looks like the dome light switch plug

 

[icanfixall]

Trailer brakes... Kinda nice of ford to install that for us too...

 

[Diesel_brad]

Looks like an aftermaket strobe plug to me. DEFFINATLY NOT FACTORY

 

[91idi]

It is factory. Got one in molly, its for the trailer brake controller. The orange tag on by the floor says ford on it

 

[franklin2]

In 89, the controller connector had a red wire(hot wire), a blue/black wire(goes all the way back to the rear bumper to feed the brakes) and a red/lightgreen wire(I believe this is the brake signal wire).

 

[foresterdj]

Good, was kind of hoping it was to plug in a brake controller (which is a future project yet). The previous owner had, well, you have all seen these kind of messes before, splices and coils of wire and taped up things and two different 4 prong plugs tied up in the frame. Just a plain mess. I had to pull my small flat bed a couple weeks ago, so have installed a new 7 pin in the bumper and sorted out a left, right, lights and ground wires for it. Cut out some of the badly broken wires and old plugs. Still need to sort out part of the mess there, but hopefully I will be able to find the wires for the brakes in the mess.

The other mess I was working on yesterday was a bunch of wires he had spliced in near the front of the box, to run power and lights to his camper(s). Besides the normal lights and accessory wires, there was a two wire cable, about 10 ga., that ran from there forward. I am thinking he must have had a window wiper on one of the campers because these ran to the battery. The hot wire fused and running through a solenoid which was powered to close via a line spliced into the hot wire on the wiper motor. I capped these off and left them in place until I can decide if they have any future use.

 

[Diesel_brad]

Why is there only 3 wires if it is for a brake controller?

 

[94f450sd]

the wire and the solenoid is to charge the battery in a camper.

 

[foresterdj]

And it goes hot when the wipers are on? It was turning on the wipers that closed the solenoid making the black wire hot.

 

[94f450sd]

thats wierd.on the truck i had it was on a toggle switch and went to the battery wires in the plugs.

 

[franklin2]

Why is there only 3 wires if it is for a brake controller?

I guess they didn't incorporate the ground wire in the factory harness.

 

[foresterdj]

I suppose not all brake controllers are the same, but I looked at wiring diagrams for several tonight and most seem to have 4 wires, but only 3 leave the cab.

Black - 12v coming to the unit from battery, via a Circuit Breaker near the battery connection
white - from neg post (ground) of battery
blue - going back to the trailer plug in and then to the brakes, &
red - going to the switch for the brake lights, on the brake pedal *

This later one, not ever leaving from under the dash, would not need to be in a plug in.

On a related note, and hopefully someone can verify, but one of the controller wiring diagrams had a special note about late 80 early 90 Fords with anti-lock rear breaks and instructed to NOT hook the red wire to the switch on the brake pedal, but to.... Dang, sure wish I could remember where it said, but hopefully any controller I might buy would include this instruction.