[miket]

I plan on building a louvered grille block with 2 actuated zones and installing an electric fan in my tundra.

I wonder if i should use the extra pins on the obduino i'm building to control it. Also i wonder if i should use a temp probe through the radiator or the obd coolant temperature reading.

My plan is for 4 increasing temperatures to, open the upper grille area, open the lower grille area, turn the fan on low, turn the fan on high.
I bought a used variable speed fan controller that has a temp probe and turns the fan on 60% at the set temp and ramps smoothly up to 100% over +10deg. Now I'm wondering if I should ditch that and use relays and control the fan with the grille controller. The used fan i bought has 3 pins for a high speed and a low speed so variable speed is nice but not necessary.