Theory Of Operation
WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.
The Electronic Shift Module (ESM) monitors the internal park switch circuit for electrical failures. The park switch input is compared to the actual shifter position. If a discrepancy is detected, the switch is considered stuck open or closed depending on the actual shifter position. If a fault is detected with the internal park switch, a DTC will set and the Key Lock Solenoid will be disabled.