Engine Speed Sensor: Description
WARNING: This page is about a different car, the 2004 Dodge Intrepid, 2004 Chrysler Intrepid, 2004 Chrysler Concorde, and 2004 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.
The PCM receives a signal from the TCM and the transaxle output speed sensor over the bus communication line to indicate vehicle speed on automatic transmission cars. On Manual transmission cars (if equipped) vehicle, a dedicated vehicle speed sensor is connected to the PCM.