Wires, What are they?

what exactly is wrong with the car? sometimes there are wires that are loose because they were cut off malfunctioning components. People will leave the old wires hanging loose in the wiring harness even though the wires are no longer needed.
So far the only gray wire showing in the engine compartment is to the oil pressure switch, I haven't found anything yet for a green with red tracer, black and brown are quite common so I'd need to narrow it down some.