Powertrain Control Module (PCM)
WARNING: This page is about a different car, the 2005 Mercury Sable and 2005 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
The PCM is on the high speed CAN. The PCM controls the engine for better fuel economy, emissions control, failure mode detection and storage. See INTRODUCTION - GASOLINE for diagnosis and testing of the PCM.