The passenger module is nearly as complicated inside as it still has the drive the window, power mirror and door lock actuator. It just have fewer switches on the front.

The only thing connecting the driver side control panel with the passenger one is a single wire called the P-bus. The P-bus forms a multipurpose network for the driver's door PM module, passenger's door PM module, general module and sunroof module. Simple serial messages are sent across the bus to all of these modules. For example when unlock on the remote is pressed the general module unlocks the rear two doors and sends a serial message to the two front door PM modules to unlock the front doors. Ever wonder why the rear doors seem to unlock before the fronts? There is a bit of latency to get the message to the PM-module to unlock the fronts.