Ok guys, I searched and could not find anything as far as a write-up for our Expy's relating to the "Brown Wire Mod" that was anything other than "cut the brown wire near the t-case shift motor". I wanted to retain the A4WD feature so I set out to make it work.
The purpose of this mod is to be able to disable the A4wd so as to have 2wd like on the 97-99 Expeditions have. Just to clarify, with the toggle switch off, you still can engage 4wd hi and low, but you won't have A4wd. I like the idea if retaining the A4wd, it hate not being able to control it, not to mention the front end drag when making a tight turn.
30a Toggle Switch
5-6ft of wire (2 strand wire, or 10-12ft single, cut in half)
Various Connectors of Choice
First you have to find what wire we're going to be interrupting the signal of.
Finding the wire in the truck was the hard part, but here is the wire in question looking under the truck. This is it on the motor side of the connector:
And this is the same wire on the truck side of the connector:
Here's where it enters into the body:
--------The above pictures are for reference only, not necessary to identify unless you want to verify its the correct wire inside the can before cutting it which is what I did--------
Don't make the same mistake I almost did and think it was the big brown wire in this harness that runs along the drivers side:
The harness that the wire we want is located in comes through the floor under the drivers seat, then makes a turn for the above harness so one would assume its be in there, nope, I checked!
I did have to lift the drivers seat out of the way because the harness enters the body directly underneath it and it is accessible through the hole in the carpet where the rear floor heater duct pokes through as seen here:
So, now is the time you get to cut. Cut the wire and splice your new wiring for the switch in line with the brown wire in the above picture. I used make and female spade connectors just in case I ever wanted to revert back to stock, but you could certainly use butt connectors and be fine. Here's a pic with the wire spliced in:
So now run your wire under the carpet toward the front of the truck. I ran mine in the channel where the console meets the floor so I wouldn't have a lump under the carpet. It should come out here:
Make sure to tuck the carpet back underneath the heater duct for optimal rear seat passenger comfort:
Now remove the stereo bezel that houses the 4wd rotary switch.
Then run the wire up through the dash (I used a stick poked through the hole the 4wd switch wires come through, and ran straight down to where the wire was in the above picture, then taped the wire to the stick and pulled it through) and zip tie it in place so it doesn't fall back through when you put the bezel back into place:
Lastly, find a place you want your switch (I wouldn't suggest to mount it where I did because I had to snip off the lower mount for the vent above the switch due to the retaining nut for my toggle was too big and needed room. Thank goodness ford put the two tabs on the side or it would be flopping all over in there!) and wire it up. I used a switch with an indicator so I needed a ground, I found one in the climate control harness pictures below, but any ground will work.
I didn't get a final pic yet, but I will.
Here're a couple test videos, interestingly enough (I was not expecting this), the led will be on all the time when the switch is on (enabling A4wd) but will be slightly dim, and will get bright when the clutch activates. I can see it happen while turning at full lock and when traction is lost. See videos below:
***If someone could please direct me as to how to imbed video, that'd be sweeeet***
Overall I love the mod, NO MORE FRONT END DRAG WHILE TURNING!!! It was driving me nuts while parallel parking making me think I was rubbing against something. But, that's gone now, yah!
Sadly, she doesn't have enough power to burn out, but I do get a chirp off the line now!!
I'm also pretty stoked I can see when it engages A4wd now, seems cool to me for some reason.
Lemme know if y'all have any questions!!