System Overview, Brief Description, Cars With Engine Management System PSG 16
WARNING: This page is about a different car, the 2002 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
Engine control module PSG 16 is not connected on the I-bus. This system needs much faster communication so that there are no noticeable delays when the control module requests a new amount of fuel per injection, a new injection angle or the like.
The engine control module is connected to a separate bus called the P-bus (Powertrain Bus). The communication speed of the P-bus is ten times faster than that of the I-bus.
The P-bus is also connected to MIU. MIU is responsible for ensuring that information available on one bus is also available on the other. Note also that PSG 16 has a separate K-lead to the diagnostic tool.