Iceman218

No help here. I have a 2021 Sierra AT4 with the same issue. Tried cleaning the outside of sensors in the corner of the bumper (in the step section) many times and focused the hose on the sensors again today. The truck is clean, but get the message just as the truck starts up so it seems the error is in history. It works sometimes but then weeks go by with the start up message "Side Detection is Temporarily Unavailable". Sure would like to know how to reset it. Update Dec 31, yesterday I drove 71 miles to my son's house and the right mirror stayed lit the whole drive. But the left mirror started showing rear overtaking vehicles about 20 miles into my drive. I tried stopping and restarting the vehicle, but the right side remained lit. Then on my return drive, both mirrors lit up at startup and both worked well at showing rear overtaking vehicles all the way home. Today, the system again is working normally. So my input is cleaning the sensors behind the rear bumper corner step is important but takes miles to reset.