4th Gen Ram 2009-2012 Fan Temperature Hysteresis

[emjohn43]

Hello all!

My truck is a 2012 Ram with a 2010 Ram ECU. 5.7L; with a 8HP70 transmission (hence the 2010 ECU).

I'm trying to adjust the on/off temperatures for my trucks electric fan. Challenge is the hysteresis cannot be reduced below 32?F; meaning for an 'on' temp of 212?F, the fans won't shut off until the coolant temp reaches 180?F. I'd like to change it to 10?F, so it can get to 212?F, and off at 202?F (right near the factory thermostat temperature).

I see on other Dodge vehicles, this setting can be reduced to as low as about 4 deg-F....so maybe it is a user error on my part?

2010 Ram Fan Temps.jpg

[jefo]

Change the units to Celsius and it will make sense. 32F is 0C, each degree C in hysteresis is about 2 deg F.