Fans not coming on

99 z28. Went carbed but still using computer to work dash. Question. I have coolant sensor installed. Dash shows temp. Hptuners shows temp. I can turn the fans on manually through hptuners scanner. But it they will not turn on when motor gets hot. Any ideas

Best I can find is computer must think car is running before it will turn fans on. Any way to trick computer into thinking the car is running