Anyone used power for onstar mirror for self dimming rearview mirror?

[RobZ71LM7]

My LT, like most, does not have a self dimming rear view mirror courtesy of brilliant GM options packaging. I can get a get a new Gentex self dimming mirror for under $50 (no onstar, just a basic model). I don't need or want onstar nor do I need a temp/compass as that is built into the dash which makes this a really cheap addition. Is the wiring for the onstar sufficient to power a self dimming rear view or should new, key-on, power be routed?

[shadetree 1]

Not sure if it will help you, but I ran into the same thing looking for a auto dimming mirror for my brother in laws 2014 impala.

 

He wanted it to look factory. Found about the same looking GM mirror with the options it had, except with the rear facing auto dimming photocell too, took it's plug/harness cut back above the headliner a bit, from a (salvaged) Chevy truck.

 

The mirror plug was different but the wiring had mostly the same color codes, just had to check each mirror's wiring diagram and change the pinouts to match.

 

The dimming mirror had the old style speaker in it, not the headliner style, but changing the wiring config, it was not connected and the dimmer was energised. Total cost $10

 

shade.