Hi guys, I just noticed a single wire under the spare wheel coming from the harness by the battery and leading to a small black box attached to the rear valance. Does not appear to be OEM as the wire is not sleeved. I have no idea what it is. The unit is 6 inch by 3/4 inch by 1/1/2 inch deep with no markings on it.
Also should there be a trim panel attached to the underside of the valance as the valance has several holes with clips along its fwd edge?

 

It looks like a fog light to me. Can you check and see if it turns on with your lights?

 

Checked with main lights, spots and fog light, brake lights on/off, no change.

 

Guess you have to take it off to see. Might be label or markings on the other side. Once it’s off, you can disassemble it to see if there are lights inside. Maybe it’s an infrared receiver for some purpose.

 

It looks sort of like an infrared sensor to me, like an aftermarket sensor for reversing.
My rear valance differs from yours, it extends further curled towards the front and has mounting points that connect to the areas where your clips are located. I'll try to take a photo.

 

Appreciate the responses.
I'll wait a while longer then I'll pull the unit for possible hints and try and follow the wire.