Hi, I noticed this plug hanging underneath my car and I was wondering what it does exactly and where it should go? (Sorry about the poor pic quality.)

 

1st guess is broken off radiator fan switch. It goes in the head between the back two spark plugs.

2nd guess is knock sensor, which is in front of the starter screwed into the block drain hole. But, I don't think that's what it is.

 

Dang, you just getting around to asking or is the clock off on your camara?

Seriously, it looks like the fan temp switch wire in the passenger head. Should be a small round post for it to plug onto between 6&8 cylinders.

 

You are correct on your first guess five7kid and I would imagine that second connector in the picture above the date goes to the radiator fan itself.

 

Cool, dont worry SMasterson its only the clock on the camera I couldnt be bothered adjusting it are you sure it isnt the knock sensor because I have been getting pinging when I floor it, it gets to about 2500rpm then it sorta hits a wall of sorts and the car slows down I can also hear a loud rattling noise.

 

The black wire goes to the fan switch and there is a white wire in the same vicinity with a connector similar to that one that goes to the knock sensor.