I have a 2021 Grand Cherokee purchased new (approaching 3 yrs ago). An odd problem started occurring a couple of months ago. When I trigger the rear hatch it opens maybe 8-12 inches then stops and closes again. If I trigger it again, it opens all the way just fine. In as little as 10-15 minutes, it will misbehave again. For example, I open the hatch at the grocery store... it misbehaves so I have to trigger it a second time. When I get home (about 10-15 minute drive), the hatch misbehaves again. I can use either the exterior handle, the button on the ceiling console, or the remote and get the same behavior. The struts hold the hatch open no problem, and in "manual" mode, the hatch seems to move freely throughout its range, so it seems unlikely that the motor is overloaded - besides, it operates normally immediately after each "problem" cycle.
The service department where I bought it has checked it out; they had the car for a day and only saw the problem occur once; they found that the battery was less than fully charged and considered it to be a possible cause; they charged and tested the battery, finding it to be in good condition. They found no faults reported by the body controller and did a recalibration (not clear of exactly what). From their point of view, they found nothing wrong, but I am still seeing the problem occur.
I have had annual rust protection applied twice - the most recent application seems to coincide with the initial appearance of this problem, making me wonder about a connection - possible contamination of a sensor or something.
I know nothing about the mechanical, electrical, electronic, or body control logic design of the hatch, so I couldn't begin to think of what could cause the observed behavior. I'm also not that inclined to do any troubleshooting or repair myself (especially since the car is still under warranty). Can anyone offer any insight so that I can get this problem resolved - perhaps give the service folks some useful guidance?
