'70 Z28 temp gauge has not been working, but feel i should tackle it this year. Gauge is new as is the wiring. When I turn on the ignition the needle moves fully to the right and then drops back to left and doesn't register any temp. The movement of the needle is exactly what I have read when u want to test the gauge, ie, turn on the ignition and ground, needles moves to right it to indicate gauge is okay? So what is my problem when it does that with grounding.