Can someone point out to me the coolant temperature sender on my 96 4.0 liter? (Picture included) also any help with a broken temperature gauge

http://imgur.com/7l3dZsc

So my temperature Gauge isn't working. Just sits down past cold. I've read I should try grounding it out and the sender for the temperature Gauge has only one wire as opposed to two.

Basically I can't find the one wire part and if/when I do, (assuming it's a plug) not quite sure how to ground it out. Do I cut the wire to the plug and touch it to the block? Stick the probe of a test light in the plug socket? Will it not be a plug at all? I'm a newb and super confused.

Any help on how to go about getting the temperature Gauge working would be greatly appreciated.

For reference the thermostat housing next to the upper radiator hose is dead center in the photo. And I'm assuming the Grey plug is the the sender for the computer system.