Theory Of Operation
WARNING: This page is about a different car, the 2009 Dodge Caliber. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Module (TCM) monitors the secondary line pressure (secondary pulley pressure) from the secondary pressure sensor. The TCM compares the actual secondary line pressure to the target (desired) line pressure. Failure to match the target line pressure over a given time will set the DTC.