The one that ends behind the front bumper (yellow arrow). It's not connected to anything, and I'm hoping it's for the factory fogs, which I don't have.

 

Maybe ambient air temp sensor for the overhead console?

 

That was my other guess, though I don't have the overhead console either.

 

Funny seeing this. I removed my bumper today and mine has the same connector and I was wondering what it was for.

...

 

x2

 

Yes it's the ambient temp sensor hookup. Standardized harness.

 

Damn, it was hoping it was for the front fogs. Here's my next question: Is there a harness pre-installed for the front fogs, or do I need to run my own from the switch? For reference, my XJ doesn't have factory fogs, so I'd be installing my own switch as well.

 

Well considering there are TWO fog lights and neither one of them sits in the center of the Jeep...

The fog harness was optional. If you didn't have them stock, the only thing you have is the wire from the switch cavity to the connector in the driver's footwell. Wiring to and from the PDC is absent, and the relay cavities are not connected. If you want to add fogs you'll have to rig something up yourself unfortunately