F80 radiator fan acting up

[Vlad_T]

Hey everyone, so my radiator fan is acting up.. I already replaced the fan relay, coolant temp sensor and the thermostat. It's not the fan because I plugged up a good running one to check and it still does the same thing. Sometimes when I just start the car, the fan just starts going crazy. It spins fast and then slow and keeps going on and off and then randomly stays off. Anyone have this issue?

[AlmondJayRoM3]

Originally Posted by Vlad_T

Hey everyone, so my radiator fan is acting up.. I already replaced the fan relay, coolant temp sensor and the thermostat. It's not the fan because I plugged up a good running one to check and it still does the same thing. Sometimes when I just start the car, the fan just starts going crazy. It spins fast and then slow and keeps going on and off and then randomly stays off. Anyone have this issue?

Since I don’t have access to ISTA or a scan tool right now I can only speak general troubleshooting techniques for something like this.

First stop throwing parts at it. That way you don’t potentially introduce more issues than what you were trying to fix in the first place. But since you replaced them don’t assume that the parts are good or not damaged from improper installation or bad wiring and connectors.

Check the input from the coolant temp sensor with your car running and verify that it is not erratic. Use a scan tool and not the temp gauge in the instrument cluster. If it is, check the wiring for and grounds or broken insulation. For the fan relay use the scan tool to activate the fan via the DME. If the fan don’t work, troubleshoot the wiring and connectors. Namely verifying a good clean voltage going into the fan relay

[G35POPPEDMYCHERRY]

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