Power door locks on right (passenger side) don't work. Driver and rear sides door locks and ALL windows/mirror operate fine; it's just the two door locks on the passenger side that stay in unlocked position. How do i troubleshoot this issue? Thanks for your help.
There's really no way around having the correct wiring schematic and some basic DC voltage testing ability to diagnose a problem like this accurately -- we don't promote part's swapping until it's a last resort.
But looking at the schematic for a 2006 Liberty (didn't give me the model year) I do see something that may affect only the passenger side door locks.
There are separate "Door Unlock Passenger and Driver Relays".
When you click on a door lock switch it sends a signal to the body control module. The module then sends voltage to activate the door lock relay (works for both) and the passenger and driver door lock relays (works for each). The relays either send 12 volts or a ground to the appropriate terminals on the door lock actuators. That's how they work -- lock or unlock by reversing the polarity (switching the power and ground applied to the actuators).
Problem could be the relay, the body control module, or a bad connection in the network of circuits.
I'd start at the passenger relay with a schematic and a test light.