The temp gauge does not move.
I checked by shorting the green wire to ground and it moved full right.
I replaced the sensor.
Still nothing.
Could this be related to air in the cooling system ?

The temp gauge does not move.
I checked by shorting the green wire to ground and it moved full right.
I replaced the sensor.
Still nothing.
Could this be related to air in the cooling system ?

Also when I turn on the key the gauge drops down a little, like a volt meter hooked up backwards.

Since the plug will only fit on one way, sounds like you may have a bad plug, or a broken wire.