Auto dimming mirrors question

[idahoruss]

I see a lot of action buying and selling auto dimming mirrors with temp and compass.

How hard is it to convert to one from a plain mirror in a 2012 GMC 2500HD work truck?

[99k1500]

If you are just talking about the rear view mirror. It is not hard at all. The mirror needs power ground and a temperature sensor (2 wires.) It also hooks up to your reverse output so that it does not dim while backing. I have done it with and without this wire. There is a good chance most all of the wireing you need is alread in place. I even took the temp / compass mirror out of our Tahoe before we sold it, I then installed it in a Nissan Altima. There is nothing to it.

Plenty of write ups on the net. Do you have On-Star? If so most everything you need will be right there. If so make sure and get a mirror with the same plug. I think there are two different plugs, 9 and 21 Pin. Or something to that effect.

I currently have a mirror from a Saturn in my Silverado. Same mirror, just the best deal I could find on ebay. Temperature sensors with wire and harness are about 20 bucks on ebay.