Temperature Gauge don't work

[Deereman]

My Temperature gauge doesn't work, there is power to the cluster, and good continuity from the sensor wire to the ground portion of the gauge. If I ground the sensor wire to the block the gauge only goes about 3/4 of the way to H. I took the cluster out of the truck and hooked a jumper cable to the hot terminal on the gauge and the sensing plug, the gauge pegged to H immediately, I then grounded the body of the gauge and it went back to C. Any idea what's going on here? I also have good continuity throughout the printed circuit. 

[DENALIA]

I am having the same issue. Someone told me to make sure I have a sending unit for a gauge and not a light. I have not been able to check it yet but when I do I will post here if it made a difference. 

[Deereman]

Okay