This multi-pin plug recently appeared under the left side of the dash, near the hood release. The only thing not working right is the oil pressure gauge. But, I think that's a whole nuther thing.
The harness disappears up and under . . . .
I can't see any empty mating plugs.
This is in a 1999 Cherokee Sport with a 6 cyl w/auto trans just short of 250,000


Mystery plug

 

Looks like OBD port. It's supposed to be disconnected unless you plug a scanner.

 

Definitely and OBD 2 port. You can get a code scanner that connects to it, and it gives the check engine codes as well as some sensor data that computer has.

 

Normally not floating free though. Needs reattached.
https://www.outilsobdfacile.com/base...2-obd-port.jpg

 

Thanks guys, I'll be looking into scanners . . . .

 

I see. . . .
The original owner had removed it to attach a controller for electric trailer brakes and left it hanging. Now it's dropped down from where ever it was tucked away.