Factory connector for 7-way "addition" on stock harness (1998)

[ratdude747]

Doing some looking and research about my recently purchased 1998 Expedition (but in title limbo for the moment, so no spending money yet)... one thing I'd like to do is add a tow hitch, brake controller, and 7-way connector for towing my boat (3000lbs roughly, has trailer brakes I added and currently use with another truck). I have questions about the 7-way connector as I'm seemingly missing a piece of the puzzle.

Context: This 1998 Expedition XLT has a 4.6 and is RWD (axle code 17, so 3.55 gears?). Due to the lack of a hitch, I'm pretty sure it doesn't have the towing package, but does have all the harness plugs for such described elsewhere on the site:





... the appropriate fuses are also present in the fuse boxes. It does have a hidden 4 way connector but is roached from years of being uncovered :


(picture of other side didn't turn out, too lazy to re-shoot. But it's full of mud and corrosion )

Anyway, poking around various places I get auto parts, I was able to find harnesses for the trailer brake controller connection, so that's a solvable problem. However, I'm finding nothing regarding the second trailer connector with the added connections to turn the 4 way into a 7 way. Before I ultimately resort to chopping the plug and splicing to said wires, does anybody make something that'll plug into the second connector? I don't mind it being a pigtail to then splice to a 7-way. Oddly, I can find the 4-way cable I already have... but everything 7-way is either generic "splice it yourself" (which is fine, if I had the other end to splice into) or "use the existing tow package cable". (which I don't have)..

Worst case, go to a JY and look for something of this vintage with a tow package and the appropriate cable?

Just trying to see what the cleanest/best way to do this is. I'm not afraid of custom wiring (my other truck is chock full of it), but if factory provisions for something I want already exist, I like to use them when possible.

 

[ratdude747]

Took a closer look... The second connector provides trailer brake and battery connections. No reverse, but I don't need reverse for anything I'd be pulling. Looks very similar to other Ford connectors... Like a 2 pin version of an O2.

I'll hit the Ford connector cross-reference chart and see what exists... Even if I have to cut off a couple of keying wings.

 

[ratdude747]

Per a look at the ford service connector book:

https://www.fordservicecontent.com/pubs/content/connectors/images/connectorcatalog.pdf

(too large to attach)

It appears the mating connector is a WPT-433. Used for many different things (RA says for a tachometer, other places say for a radiator fan)...

Looks like I just need to get one of those pigtails/conenctors (ideally with a nice and heavy wire since we're talking 30-40A per), chop my ugly 4 pin, and splice both pigtails to a new 7-way connector.

At least ford used "standard" wire colors on the existing harnesses...

 

[AWAR]

I upgraded the basic trailer to the hd package on my Gen 2. The rear harness attaches in front of the drivers side rear tire outside of the frame. I extended the charge, brake and reverse wires the rear of the vehicle. I used these online manuals, here is one for your truck.

 

[ratdude747]

Ah... mine's behind the wheel under the taillight, attached to the bumper bracket.

It seems the backup wire is in fact available... it's on the 4-way cable, specifically on the 4th pin that the 4-way doesn't use (C411). The trailer brake connections (Battery charge power and the brake control) come in on the C412 connector. And the ground, well, is a frame ground.

Going back to the ford service connector book, that connector used (per a look at commercially available replacements for the 4-way cable) is a WPT-111. A commonly used connector for O2 sensors (but like with the other connector, the gender's backwards with the male connector upstream of the female)... this would be the "harness" side of such a connection (no bilking a pigtail off a dead O2 sensor, dang it )

So, I guess I have a gameplan then... generic 7-way connector (or the parts to make one with some cable on all connections), A WPT-111 (or equivalent) pigtail, and a WPT-433 (or equivalent) pigtail. Once the vehicle is street legal, I'll put it on the project list.

 

[ratdude747]

After some shipping and handling delays... I finally received the hitch. I had made up the new harness a couple weeks ago, but didn't do anything with it until the hitch was installed and I could confirm fitment.

To mount the 7-way connector, I bent, cut, and drilled the factory 4-way bracket and bolted (with loctite) the 7-way bracket to it:



Fully installed:



Do note that I did have to trim the bumper plastic. Mounting lower would have hit the tow bar.

Pics of the harness installed and dressed:



(The pigtail service numbers in a prior post are indeed correct. Fit Great!)





It doesn't quite look factory, but good enough for my uses. I did previously dry-test the harness with my boat trailer (and the trailer brake controller already installed and wired) and everything that I could test worked (Reverse *should* work, but none of my trailers use it and I was too lazy to probe it).

If all goes to plan, I'll be testing it with the boat trailer this coming weekend. Yee haw!