dodge 3500 cummins clutch fan engages on flat with no load

This is interesting. I beleive my gague is very accurate. I had a and android app picking up the temp off the ODB and it matched the analog gauge. I have not hooked it up for htis problem.

I understand from the cummins forum that I might have a 200 degree thermostat?

My hunch is the water pump. I am hearing a sqeeak from something on the serpeintine belt, the truck has 205,000 miles so it's about due, I'll check it tonight.

thanks