OK, I just spoke with Gary at Perfect Pass, He told me if you have the upgrade the temp will read from the old PP paddle wheel.

If you go from Moomba Cruise to the PP Stargazer then he needs to send me a "custom" wire that will go from a hanging connector behind the dash with a brown and a white wire that comes from the OEM Moomba paddle wheel, to the brain of the PP unit.

I am not sure why they wouldnt include this wire when I bought the unit, but he told me it would be $12 if I wanted him to send it to me.