The bit you're looking for looks like this one: https://www.ebay.co.uk/itm/Rear-Sliding-Door-Door-Lock-Actuator-For-Chrysler-Voyager-Dodge-Grand-Caravan/182550266453?_trkparms=ao%3D1%26asc%3D20170912102017%26meid%3D93411373f2d64380a28e2f19b808edb9%26pid%3D100706%26rk%3D1%26rkt%3D1%26&_trksid=p2045573.c100706.m4781
Hi there, Presuming it won't work with any of the locking controls, the switch on the drivers door as well, then start with the central locking actuator in the offending sliding door, swap it for the other sliding door one to totally confirm, same motor but different arm.