Mystery wiring harness

Here's a little puzzle:  I'm finishing up replacing the ignition wires, and I see this little wiring harness dangling between the starter and the frame on the passenger side.  It ascends toward the block, and joins in with two other bundles before disappearing into the larger one on the wheel well.  I can't find any obvious socket looking for its pocket rocket -- any solutions from the experts?

That is the connector that goes to the (broken) temp sender in the head. The one that sends signal to your temp gauge on the dash (that I will guess never moves?). I believe the end of the sensor connection is still stuck in the connector. Once you order the new connector, that will make sense. The car is running fine since the PCM gets its temp info from the sender on the water pump.

You, my responsive and perceptive friend, are a gentleman and a scholar. Thank you!

You're correct that the temp gauge hasn't moved in a long while. My next question to you: will the fact that this sensor is broken interrupt the signal from the gas tank to the gas gauge? Both stopped working, and my assumption was that something in the dash had gone wrong when I installed a new radio. You might be slaying multiple birds with one stone.

No, all separate problems. You're welcome, I've fixed this problem more than once. Make sure you get some good heat protection on the new sensor and the little green wire. The wire is a very thin gauge. Stock, it has an aluminum tube. I use that along with some wraps of aluminum peel and stick duct sealing tape (NOT "duct tape" lol).