The fan runs on 12 volts from the FCM. There is an ignition sense lead that turns the FCM on, and a "PWM" lead that comes from the PTCM.

The PTCM sends a tickle pulse to the FCM every few milliseconds. The FCM responds with a pulse. As long as that happens, the light stays out. If the PTCM does not get a pulse from the FCM, it lights the light to tell you that you have a cooling system problem.

The width of the pulses from the PTCM tell the FCM how fast to run the fan. The FCM sends pulses of 12 volts to the fan motor (your meter will average these pulses and imply to you the fan is getting 4 or 5 6 volts, but that is not the case). DC motors do not do well on low voltage, they do better on pulses of full, normal voltage to control speed. I have a switch in my car that breaks the PWM wire connection - this makes the light come on, and it ALSO means that the FCM does not see the pulses from the PTCM - this makes the FCM go into emergency mode (because it no longer is being told what to do) - and the FCM puts full voltage on the fan motor and it runs like a turbine!

Oh, most likely reason the fuse blew was that the motor is going bad and drew too much current. It COULD be an issue with the FCM, but I really think it's the FCM- but it's hard to say from here.

Hope all of this helps.

Oh, and Bacon. Always eat bacon.