I have just the opposite problem with mine. Wants to read hot even though actual temp is 180. Also tried different senders for different vendors. 1958 Chevy. Also a new gauge. Still shows hot when it ain't.

But if yours moves when grounded and works with test light, then the sending unit may be the culprit. You say you used a laser thermometer to check the heat, is it indeed running where it should heat wise yet your gauge isn't showing? Maybe thermostat stuck open or missing?

Last edited by Roy Rodgers; 01/03/2014 2:44 PM.