Theory Of Operation
WARNING: This page is about a different car, the 2013 RAM 1500. However, it is still accessible from the selected car via links, so may be relevant.
The purpose of the diagnostic is to monitor the park sense circuit from the RF Hub. The RF Hub supplies B (+) on the park circuit to the TCMA. When the transmission is in park, the TCMA will ground the park circuit indicating to the RF Hub that the transmission is in park. If the TCMA detects an open or short to ground on the park circuit, DTC P1DCA will set.