Radiator electric cooling fan won't turn off, runs constantly

This vehicle as with other General Motors products can experience a constant fan operation for a couple of reasons. The vehicle should be checked with a bi-directional fully functional scan tool. The technician should do a thorough assessment of the mechanical abilities of the cooling system, to include a system that is full and circulating. The thermostat should be observed for proper operation closing and opening as well as being non-functional meaning stuck in the open position with this particular issue. If the vehicle while being monitored by the ECM sees that the car takes an extended period of time to come to temperature the car can set a code and then put the fan control circuit into an override and keep it engaged at all times as a safety measure. If no overheating is or has occurred suspect a stuck open thermostat or a possible PCM failure though the circuit for the fan control should be thoroughly tested looking for a short on the ground side of the circuit prior to its proper grounding point.