Does this wiring diagram help?

https://mopar1973man.com/external-media/image/4thgen/2018wiring/body/seats/memoryseats.png

I would have thought with the power those motors need they'd be running at 12V. If you check what voltage the passenger seat uses driver should be the same.
Another thought- make sure the ground ion the seat is good. When I swapped seats in my 2014 Charger it was doing some weird things when the ground was loose.