64 Valiant IVR test

OK, I just did the temp sender wire check and as mentioned the voltage on my digital jumped up & down. I'm guessing the regulator/limiter is an all or nothing function.
I can live with knowing the temp sender works and what range it displays.
Next time my tank is empty I'll pull the sending unit and check it's range. It may be an aftermarket replacement unit, so I understand that can be suspect.
Thanks for the info.