A couple of my gauges aren't working properly and not sure where to begin. my coolant temp wasn't working but that sensor was simply no plugged in now it works fine. My RPM gauge however as soon as you fire up the car it rolls all the way from 0 to the opposite side of the gauge lol. also the oil pressure gauge isn't working but that is most likely I assume a bad sensor? looking for some assistance with the rpm gauge issue and if you think in am wrong about the sensor for the oil pressure lemme know what you think I should be looking at. thanks

The oil pressure sensor should have 0 ohms at 0 pressure and 90 ohms at 60 psi.

grounding to chassis during this test?