That runs along the drivers side of the frame? One end goes towards the transmission the other runs along the frame towards the rear of the truck and it is cut off.
94 4x4 automatic 3.0
i am getting body work done I can’t take a picture. Or see any colors of the wire.

I will get pictures when I get home it will be a few weeks. I noticed it as I was leaving to head to the airport.
It looks factory where it’s dead ends is about where the cab and bed meet it’s cut off. it’s on the frame in clip holders it’s in a plastic ribbed cover/jacket like all the other harnesses the other end ran along the frame towards the transmission. A friend said it could be a o2 sensor that was past the muffler before it was modified.

Yes everything works brake lights, tail lights license plate lights all work.

Wire for the o2 sensor?

I would insulate them and keep them separate at least.

Are those the only wires in that harness?

Yes I peeled the jacket back about 8” and the 4 wires wer the only wires in the harness.

Are they cut close to the catalytic converter?

It’s cut against the frame about the area the cc is located.

If so, I am pretty sure those are for the rear Oxygen Sensor for a Catalyst monitor.

Do you have a "check engine" light on?

No cel

Your model may not require the rear oxygen sensor.

Thanks for everyone’s help!