My drivers side rear door is locked open and I

Do the windows work? Does the door lock work on either front door?

You have a motor that actuates the lock, and it has failed, you must remove the door panel and replace that part, you will need a drill and a large pop rivet gun to install the part like the factory does, You will also need a rivet head cutter for the drill.

These doors are very complex and there is not really any service except cleaning and lubrication of the moving parts that that the owner can do. Any other issue requires the dealers help and special tools and skills. So clean and lubricate (use spray Lithium white grease) all side door tracks and latches and see if that helps.

check the switches in the door pillars first then the rubber boot where the cables go from the door to the door pillar

you need to buy or make a clip removal tool. it looks like a sturdy 2 prong fork to pry off the plastic clips.this id whats holding the interior panel and some screws holding the door opener

Can't find confirmation on that running through BCM,(body control module) but I have a suspicion it does, seeing how all door locks, rear window defroster etc are all through the BCM. Might be worth it to remove battery cables, then remove connector to BCM & clean all the connections/contacts good & retry it just to see if that helps in any way.

oh we have a 02 C T & C and our keyless entry for the sliding doors. when the side doors are not closed all the way or opened all the way the keyless entry won't kick in. try doing it closed or fully open, if this does not work try checking the battery in the remote. over all lets put it this way the 02 C T & C is like the best mini van around however it comes with alot of problems from ac. to tail lights

Replace the lock on the rear door. If a used lock is used it has to have the powered door. I am a car dealer and have replaced about 8-9 of them. I sell a lot of Town & Country vans. The 1st one I paid a Chrysler dealer to fix. About $200. After that I fix myself. About $70- $125 from a Chrysler dealer new with discount. The lock is not sending the correct code to the computer and the door is confused on what to do. Only 3 torx bolts to remove and the door panel 2 screws in handle then snap off.
On one I had that did not fix the problem and it was a relay sensor about $40. on the working arm / motor of the door and not the lock. Look at car-part.com for used parts. Thanks, Roy

clean out both tracks,they are dirty

sounds like your solenoid is wearing out or wiring connections need cleaning refer to repair manual from either haynes or chiltons and under electrical section follow instructions on testing also I noticed when I had similar problems with customers it actually helped to change the batteries in the remote unit itself but not always, alot of times I had to either clean or replace solenoids