Since you were able to turn low on with the scan tool, that leads me to believe the IRCM, fan motor & associated wiring is good & that the ecm is able to control the relay's in the IRCM. Possibly ecm is not getting correct signal from coolant temp sensor? Does the your A/C system still work & does the low speed come on with it? Do you know what temp the high speed is coming on at-low speed temp 195? or high speed 210?