Quote Originally Posted by 99LS1 View Post
I am looking for all the wireing to hook up my rear view mirror with temp guage. My 99 sierra didn't have one, and I would like the factory stuff.

I've done this swap before. You need the newer style mirror with compass and temp, the temp sensor, and a custom wiring harness (I made mine). You can reuse the plug it has now but you have to add two wires for the temp sensor and run them to the front of the truck to the stock sensor location. The power and ground for the lights also powers and grounds the internal compass and the brain. The plug in is the same on both mirrors. I did this on a 99 I added an 01 compass temp mirror to. The factory wiring on the newer ones is part of the headliner harness which is too much of a pain to swap just to get two more wires.

I may even have a mirror. I'll look in my stash.