Since we bought the Envoy, I occasionally do some browsing on a Trailblazer/Enovy website and forum, http://www.trailvoy.com/. It seems that many other people miss the same features on their interior rear view mirror, and someone had done some research and written an article on how to add a mirror with these additional features. The article can be seen HERE.
The first step was finding a donor mirror. This was a little more difficult than I thought. Since our Envoy was originally a rental car, it was ordered without OnStar. The issue this was creating is that most cars come with OnStar and have it mounted on the rear view mirror. So, finding a mirror with the compass, temperature, auto dim features, and passenger air bag light WITHOUT OnStar was challenging. After a little searching on eBay, I found one out of a totalled out 2006 Chevrolet Silverado pickup. The company that sold it is LKQ Corporation and were very easy to work with. The mirror arrived in a few days and was in really good condition.
The next step was getting a few smaller parts. I needed the Ambient Air Temperature Sensor (GM Part #15047946), wiring harness with pigtail (GM Part #12101856), female terminals (Delphi Part #12191818), and cable seals (Delphi Part #15366021). I ordered the Ambient Air Temperature Sensor and wiring harness from Rock Auto and the Delphi parts from Mouser. I had a very good experience with both these companies.
Now, onto the installation. If you would like in depth details of the installation, refer back to the original article HERE. First, I removed the cable cover which was held in by a clip on one end and a grove on the other. Removal involved collapsing it into itself. Next, I unplugged the existing wiring harness. Then, using a Torx driver, I loosened and removed the mirror mounting screw. Now, slide the old mirror off, slide the new mirror on, then install and tighten the mounting screw, plug the wiring harness in, and reinstall the cable cover.
After we got the parts installed and the wires ran, we got the Envoy back together, turned the key on, and everything worked!! Once again, I have an interior rear view mirror with the compass, temperature, and auto dim features! Overall I was very happy with how easy this installation was and am very thankful for finding the instructions on TrailVoy!







