On my truck next to the fuse box and ignition module there is this other heat-sinked component and I’m not quite sure what it is. It has a ground wire going to it from the side of the fuse box and then a crappy aftermarket splice into the trucks harness. Then the output wire is black and goes to the back of the truck, but before it reaches the rear it is butt connected and changes to red then further on just lays at the back with no connection to be made. I see as of now it has no purpose, but I’m wondering if anyone might know it’s original use and what the factory wire it splices into is. It hasn’t caused any problems for me yet, but I will be taking a trip across the country and want want to get the truck ready for it. Any help would be greatly appreciated.

 

Just a shot in the dark, but it appears to be a giant transistor to control the motor speed of a salt spreader that was long ago removed. That style of motor controller hasn't been common since the early 90's but I have seen a few on tractors and trucks from that era.

 

i cant tell you what the grey/yellow stripe wire is but from the size id say its an ignition switch wire? maybe.. but if it is, id fix that by removing that junk because it wasnt done right and you can see the wire splice is pulling apart

 

Thank you, you might be onto something there, the trucks originally from Canada and then at some point made it’s way to Oregon where I bought it last year and drove it down to Texas where I live. The truck has almost zero rust anywhere and where it does it is barely even on the surface. Incredibly clean in my opinion if it was use to spread such a corrosive as salt.

 

Yeah I was thinking it might be, I’m about to prove it with me power probe and see what I get off of it. And absolutely I’m going to remove it, more of a curiosity of what it could have been at one point. If anything I’ll dig through my Ford Dealership Manuals and see if I can find any electrical diagrams what cover that wire.

 

If that was a salt truck, there wouldn’t be much left by now, imho…

 

Thats what I was thinking, but the trucks in near mint condition underneath which makes me doubt the salt idea

 

Dollars to donuts, that is a battery isolator, for a Camper or Trailer charging circuit, so if you leave the trailer/camper power hooked up to the truck, it won't run the starting battery dead.

Regardless, it's not a Ford part, and something added aftermarket.

 

That white wire, from it, looks like fried bacon, and even, looks like the red wire underneath it is cooked black crispy, also. I'd cut the white wire out now, on both ends.

 

Yup, battery isolator, for dual batteries, or battery in camper/trailer.
The wires are probably shorted, or someone tried to run a microve off an inverter, overloaded the system, fire waiting to happen.

I'd disconnect, and pull all wires, all the way out. Then fix the factory wires correctly.
By pulling the wires, you'll maybe find out what caused the meltdown.

 

Thank you everyone, a battery isolator makes sense to me and I’ve already removed everything and repaired all wiring since photos were taken. I’m a marine electrician by trade so 12v anything comes easy to me, just didn’t know what the component was and trying to understand the history of the truck more.

Agian I thank everyone who sent out an idea, and thanks for helping me figure out more about the truck. Y’all have a good day.

 

If you have dual batteries, I gotta agree with this. Having done a few years ago. I would say trace the wires, and disconnect the wires, if you don't need to isolate the batteries to prevent drainage.

 

I do not have dual batteries, but the component has been removed and all wiring fixed, no issues before, and definitely no issues now.