Hi, I'm trying to copy your work into my project.
Unfortunately I've to deal with 8 Heaters: 4 Beds and 4 Extruders.
I'm having the 'new' version of BL Touch

I tried to use the FAN2 as it seems promissing.
The probe is doing it's self-test but doesn't react to any retract, deploy messages.
Even when I just try to send the M280 P22 I1 S10 ; M280 P22 I1 S90; manually.

As the Heater pins are working, I guess I missed something else...
Right now I don't have access to my scope, so I'd like to avoid any risky actions..
My first guess:
May it be possible that I have to put a pull-up resistor between 5V and the PWM of the FAN?

Note to all guys: Yeah 4k7Ohm Pullup to 5V is resolving that issues

Sorry for bothering you, next time I'll considering checking the Circuit before asking.
BTW: Thanks for the idea with the Fan PWM Googliola
Cheers,
Roland