If the door lock actuators (integrated into the door latch assembly) are noisy and/or not working, the latch should be replaced. For some model years, the actuator for the sliding door is available separately from the latch.Google+
Car Problem Reports
Plymouth Grand Voyager New Latch Assembly Will Solve Noisy Power Door Locks
Plymouth Grand Voyager Problem
Average Mileage: 104,000 mi (70,000 mi - 138,000 mi)
Both drivers and passenger door power door lock actuator/latch assemblies noisy and unreliable. Bought used pair from salvage yard, one had same problem. I took one apart and found the problem. There is an internal clutch in the gear train between the motor and the lock lever. This clutch requires a certain amount of drag to work properly. In time, for whatever reason, this drag diminishes until the motor will spin freely without engaging the final gear to the lock lever.
My solution, and it seems to work reliably, is to drill a hole in a specific spot on the plastic gear housing, and install a screw. With the actuator on the bench, I tighten the screw in until the clutch starts working properly and reliably. There's no reason this shouldn't keep the gear train operating as long as it did before failure the first time, and then it will be a simple matter to tighten the screw some more. I have taken photos of my assembly with the screw installed to show others the specific spot to drill. I'll be happy to e-mail photos if requested.
Another thing that may help this repair last is I disabled the auto-lock at 16 mph feature so they are not constantly operating with every trip. The disabling is a very simple procedure outlined in your owners manual.
Both locks on the driver side dose not work. I always have to use the key to lock and unlock.