Chuck TieDye

I'm working behind the dash in a 1984 Chevy G30 that was long abandoned. I am trying to identify something so I can a)find out where it goes and b) does it still work.
It is plugged into the back side of the gauge cluster on the top right corner, above the gas gauge. It's a wire, 24-30 inches long with an odd little plastic piece on the end that may be some kind of sensor. It was already loose on the end away from the cluster so I don't even have a i.d. clue from locstion.
Thanks for any clues you may have for me.
1984 Chevy G30
350 engine

Kazoocruiser

That goes to the ashtray for lighting.