Theory Of Operation
WARNING: This page is about a different car, the 2012 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
The brake switch signal must be active before the shift lever can be moved out of the park position. The Shift Lever Assembly (SLA) Electronic Shift Module (ESM) receives two brake switch signals. The first signal is a CAN C Bus message sent to the shift lever assembly. The second signal is a hard wired brake switch signal to the shift lever assembly. The CAN C Bus message is the primary brake switch signal and the hard wired signal serves as the backup brake switch signal.