1. Cooling Fan Relay: The cooling fan relay is responsible for turning the fan on and off. If the relay is stuck in the "on" position, the fan will continue to run even when the engine is off. Check the relay by swapping it with a known good relay. If the fan stops running, the relay is faulty and needs to be replaced.
2. Cooling Fan Switch: The cooling fan switch is responsible for sensing the temperature of the engine coolant and turning the fan on when the coolant reaches a certain temperature. If the switch is faulty, it may not be sending the correct signal to the fan relay, causing the fan to run continuously. Check the switch by disconnecting it from the wiring harness and grounding the wire that goes to the fan relay. If the fan turns on, the switch is faulty and needs to be replaced.
3. Wiring: Inspect the wiring between the cooling fan relay, the cooling fan switch, and the fan motor. Make sure that there are no loose connections or damaged wires. If you find any damaged wires, repair or replace them as necessary.
4. ECM: The engine control module (ECM) may also be responsible for controlling the cooling fan. If the ECM is faulty, it may be sending the wrong signal to the fan relay, causing the fan to run continuously. You will need to have the ECM diagnosed by a qualified mechanic if you suspect that it is causing the problem.
