Just bought a 2021 Sorento, used the wipers for the first time today and noticed that the rear wiper runs when front wipers are turned on regardless of rear wiper switch setting until vehicle is put in drive then it stops. Rear wiper resumes when put in park. When in any other gear rear wiper responds to rear wiper switch setting. Is the normal?
No, that's definitely not normal behavior. What you're experiencing sounds like a glitch related to a specific convenience feature Kia builds into their software called Auto Rear Wiper (in R). Normally, this feature is designed where if your front wipers are running and you shift into reverse, the rear wiper automatically activates to clear your back window and improve visibility while backing up. Once you shift out of reverse and into drive, the automatic rear wiping is supposed to stop, and control goes back to the manual rear wiper switch.
In your Sorento, it sounds like the body control module (BCM) or the gear selector sensor is getting confused. It's inappropriately applying that "Reverse" wiping logic when the shifter is resting in the "park" position.
Here's a quick test you can do. Go into your infotainment screen and navigate to Setup > Vehicle > Convenience and look for the Auto Rear Wiper (in R) setting. Uncheck the box to completely turn the feature off. If turning that setting off makes the rear wiper stop acting crazy in park, you pinpointed the exact software logic loop that is glitching out.
Regardless of whether that temporary fix works, since your Sorento is a 2021, this electrical/module issue should still be fully covered under Kia's 5 year/60,000 mile basic warranty. You should take it to the dealership, demonstrate the issue (or show them a video of it happening), and have them re-flash the BCM or replace the wiper control stalk.
