Radiator fan not turning on

The fastest way to test the entire system is to unplug the two-wire coolant temperature sensor. The Engine Computer will turn the fan on by default in case the engine is overheating and it has no way of knowing it. Doing this will set a diagnostic fault code and turn on the Check Engine light. Once reconnected, the light will be off the next time the engine is restarted. The fault code will self-erase after fifty engine starts.