In my 2001 LX, the passenger door will lock and unlock when the either the driver's door is unlocked with the key or when the either driver's lock button or interior lock/unlock switch is manipulated. It will also unlock when the lift gate is unlocked. However, when unlocking or locking the passengers door with the key or manipulating the passenger's button (the switch doesn't work) no other door is locked or unlocked. To me this doesn't sound like an actuator problem. Does this sound like the Multiplexer Unit?