How do I fix the fan that cools down the engine

This fan is controlled by the engine processor through data received from engine temperature sensors. There is a relay and a resistor in play, as well as the fan motor. Testing should be performed to verify that the engine's processor is getting the right data, that a command is sent to power the fan motor, and that the motor still is not turning on -- leading testing to check the relay and resistor as well as the motor.