They have three connections, 12v hot, switched 12v and ground. However most if not all wiring harnesses made without homelink factory installed don't have the switched 12v anywhere near the maplight. You can just grab 12v and ground up there and attach it to the homelink mirror such that it is powered all the time. It draws almost nothing. If the new mirror is also self dimming, it will draw about 6ma continuously which is not an issue. I installed the 6ma version eight years ago and the original 12v battery lasted until last year. Note: The attached pdf shows the maplight 20 pin cable where I accessed 12v and Gnd. Not switched ground and not the door open gnd. In the back there are pics and comments on how to run a cable down the side pillar to access a switched 12v from the fuse panel. I did not do this.
I have to check if i have one left. But im increasing the price. Last one i only got $11 after shipping and paypal fees
Just want to say I bought one from OP. Came packaged to survive a nuclear blast and the mirror looks great. Haven't tested/installed yet but everything looks great so far!
