08 RZR 800 TPS set

I have read post after post on how to set the TPS but I am not getting voltage readings with my 2 meters. I don’t understand that. And why does the polaris manual say that the diagnostic pigtail requires a 9V battery connected yet following post instructions that is not required? I’m confused as to why this is proving to be so difficult to adjust. I have tried every DC voltage setting on 2 meters and cant get a good reading. The numbers never stop changing!