4.0 engine cooling fan runs as soon as the engine is turned on and stays on forever or until the engine is turned off!

Just as it should do!!.. Is the engine overheating during extended idle or in stop & go traffic ??

Just as Pushrod said. It will always turn as little, it is a mechanical fan and not an electrical one. When it heats up, it will lock up and spin faster until it cools back off. What's the problem?

scan codes.test cooling fan relay and sensor.