Theory Of Operation
WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. 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 Shifter lever assembly 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 hardwired brake switch signal to the shift lever assembly. The CAN C Bus message is the primary brake switch signal and the hardwired signal serves as the backup brake switch signal. These two brake switch signals are compared against each other to verify proper brake switch operation.