All 650Fs How to diagnose non operating fan

[Arion]

My radiator fan hasn't been turning on. Wouldnt turn by hand so I took it off and lubed it up and it spun when powered directly. Now I'm stuck, how do I tell if the sensor is bad or if the computer is the problem

 

[baugustine]

Radiator fan is commanded on by the ECM when a predetermined ECT is reached (somewhere around 220 F). You should jumper the relay to make sure the circuit works properly. If so, you would need a scan tool to view the ECM ECT to verify your bike is hitting the predetermined temperature. There is also most likely a data PID to show fan request, which would verify the ECM actually commanded the fan on.