mirror pigtail wiring diagram needed for bench-testing heating element

My mirror on the right hand side won't heat. Replaced once and still doesn't heat. I wanna bench test the old mirror and put a meter on the connector inside the door to make sure defrost signal is getting to the mirror or not. anybody know the pin set-up?

Do you know if the Dakota (2007) has the rear defrost option, does that indicate that truck automatically has the heated mirrors? (I assume that there is no separate switch for the heated mirrors.) Is there a place to check installed options using VIN?

Thanks,
Mark