HVAC controls heated mirrors pin layout

[cerial]

I hate when the factory does something stupid and tend to fix things with maintenance in mind.

Case in point the 01 K2500HD had a bad heater core and the radiator neck was cracked.
So I went with a all aluminum radiator with aluminum sides that was a direct drop in replacement for the plastic tank side one, replaced the plastic Y fitting with a aluminum one, and tore out all the factory HV/AC replacing it with a summit heater.
This is my tow pig/winter beater and function is the name of the game here. I started driving it last week and I still have a few small issues to deal with before the temp drops into the negatives. But, heat and cooling wise this girl is much better.

One thing I did not think of when I removed the HVAC control panel(etc) and taped up the connections was that by doing so I would loose my heated mirrors. Now I could simply run a wire and a switch. But hey I already have the wiring, relays, and such sitting in the truck.

All I really need to do is find what pin on one of the 2 connectors goes to the defrost switch(on the now missing panel) and then run a push button switch(with a light) to the other pin going to the relay and I will have heated mirrors that work just like factory.

But after hours of searching I am having trouble finding just what pins to connect. Anyone know what pins to soldier into to complete this connection?

Much simpler layout with a soon to be added button.