[Calvin]

I just tested it, works fine for me!

For the source,
- Red and Black to external 12v

For the reciever, took a PWM wire...
- both ground wires to black
- white to white
- ignore green (unless you want to reverse the logic)
- Red to external 12v

Than connect the PWM wire to the Digital input.

For a simple test without adding additional code:
- Connect the switch to Digital Input 18.
- And a spike to Relay8 (make sure nothing is connected to the spike m+m-, you don't want to turn something on)
- Now just move the source and reciever around and watch the spike light turn different colors.