The harness you REALLY want is from a 1990-92 Ranger
Second choice is a 1991-92 Explorer.
Third choice (more complexity) is a 1993 Explorer harness
on your vehicle you do not want and really cannot use
a 1993-94 Ranger harness.
They completely re-arrainged the engine bay on the rangers for 1993.
The computer lives on the drivers side of the firewall, the battery is moved to the drivers side... it makes it an impossibly ugly job
I'm bumping this old thread to vet out if what's said above would also apply to my situation where I'll be putting a 4.0L into a manual transmission(T-9) 1989 Merkur Scorpio currently equipped with a 2.9. The 2.9 in the Scorpio is largely the same as the one from a similar-era Ranger, but certainly there are differences. The PCM is located the same as the '90-92 Ranger, in the passenger side cabin. However, unlike the Ranger, the EEC-IV harness is for the most part stand-alone from the body harness, so there's no way I can avoid cut & splicing. That's fine, I've done that sort of thing before.
Given the above, I think what Allan indicates above still applies for me, but a little less so since I'll be hacking up the donor harness regardless. There's some benefit to having the harness routed towards the passenger side, just to keep the routing the same. I realize that changed for the Ranger starting in 1993, but did the Explorer keep things over there through 1994?
I'm also thinking I'll have some flexibility in what PCM I use. I can move pins around and add/delete as needed. Ideally I'd use one with dual O2 inputs (one in each manifold), no EGR, and DCL, as found in the '93+ (I think) EEC-IV PCM's. Was there much movement in pin location between the years? I can and will check schematics when the time comes - just trying to get a general sense right now.