No Power to Onstar unit

noid75 · January 31, 2017

Has anyone had an issue where no power is going to the rear view mirror and Onstar does not work? I have already checked the fuse box on the driver side and under the hood. All fuses are fine. I have also taken the mirror and swapped it with the one in my Pontiac and it works just fine in the Pontiac but the one from the Pontiac does not work in the truck. So the issue is not with the mirror unit. I have tried looking for wiring schematics with no luck. I have a 2013 GMC sierra LE Z71.

redvett · February 1, 2017

_{Go to ALLDATA for a wiring diagram.}

BlackZ71Silverado · February 1, 2017

Sounds like you have a bad wire in the harness of your Sierra....Hope you can get it repaired but electrical issues like that are a major PITA.

A wiring diagram would be the best place to start, take your time going over the harness.

UltraNutZ · February 2, 2017

is it JUST the onstar not working or is it everything related to the electronics in the mirror when it's in your truck?

noid75 · February 3, 2017

is it JUST the onstar not working or is it everything related to the electronics in the mirror when it's in your truck?

Everything electronics in the mirror.

UltraNutZ · February 4, 2017

Connector plugged in back of mirror, pin 8 is ground (black wire). Connect one end of test light to +12v and then make sure you have continuity there. The harness runs down left pillar to kick panel where there is another connector. Also pin 13 (yellow wire) is +12v power. Make sure you have power there also