temp gauge

[putnam00]

so I'm trying to get my temp gauge working correctly. it always just pegs to hot. I have an extra gauge I hooked up the spare and did the same thing ok I'm shorted to ground so I got the other gauge hooked it up by the marks on the side of the gauge + batt, S sender ,G ground then turned the key and first time the engine was cold but the gauge was in the middle like normal running temp take it off the sender doesn't move, touch the sending wire to ground pegs it, what should be the resistance to in the resistor off ground and the top post off the gauge