bobster:
I seem to have the Mosfet wired in OK. I had it controlling a 9v led, fading up and down perfectly. When I wire it up to the 16v track...
Just how are you doing that?
Which PWM pin are you using?
If you digitalWrite a "1" to it does it go full on, and, if you digitalWrite a "0" to it does it go off?
It's running a motor, basically, but I'll bet there's no "flyback" diode across +V and that module's D terminal.