I have an 18 F150. No heated mirrors from factory and no rear window defogger. I would like to wire the new mirrors to get the heated function to work.

 

Find a set off a XLT w/ turn signals, that have the 8 pin lay out. They are plug and play. Heating elements turn on when you switch on the rear defroster.

The hard part is finding some one who will let them go for non-rape prices. All these folks have installed tow mirrors prefer to hoard old parts in their garages rather then hook a member up. Everyone wants $150+ for mirrors they will never look at again. For an additional $50 bucks I would rather go Aftermarket Tows. Sigh.