This ain't my first rodeo, regarding electrical issue discussion!
LESSON LEARNED: Accurate and precise IDENTIFICATION of the components under discussion is necessary for meaningful dialog.
So, WHAT switch was replaced? What did the switch control? What circuit was involved? What significance/relevance resides in the fuses?
These questions might be answered by REFERENCE to the Generation 1 KLR650 wiring diagram on the web.
I'll try to post a URL to the wiring diagram by editing this post.
Here you go:
The WHITE wire to the fan relay is constant + 12 VDC.
If the fan runs when the ignition key is turned on, looks like somehow the fan relay is picking up a ground when the ignition switch is turned on.
IMHO, a manual fan switch remains an elegant solution to a non-existent problem: The automatic THERMAL SWITCH installed in the lower radiator AUTOMATICALLY turns on the fan, when coolant temperature reaches its threshold level. BTW, I have a manual fan switch. Fun to play with, I guess, should I wish to delude myself that I control coolant temperature, when actually the stock cooling system stabilizes engine operating temperature within safe limits.
CAVEAT: Comments apply to Generation 1 only; Generation 2 fan circuit varies markedly from its predecessor.