I asked the same question last summer and never got a good solution. I've just learned to distinguish between when the fan is running (bright LED) and when the wind is pulling it (dimmer LED).

I thought about wiring to the trigger side of the relay but that won't tell me if the relay goes out.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.