Description And Operation: 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.

In vehicles not equipped with the optional PEKG system, the Sentry Key Immobilizer System (SKIS) control circuitry integral to the Body Control Module (BCM) includes a Radio Frequency (RF) transceiver. In vehicles equipped with the optional PEKG system, a Sentry Key antenna is not used and the Radio Frequency Hub (RFH) includes the SKIS control circuitry.

In vehicles without PEKG, the SKIS circuitry transmits RF signals to, and receives RF signals from the Sentry Key transponder through the tuned Sentry Key antenna enclosed within the molded plastic antenna housing. If this antenna is not mounted properly around the ignition lock cylinder housing, communication problems between the SKIS control circuitry and the transponder may arise. These communication problems will result in Sentry Key transponder-related faults.

When the status of the ignition switch is On, the SKIS control circuitry transmits an RF signal to the transponder in the ignition key. The SKIS then waits for an RF signal response from the transponder. If the response received identifies the key as valid, the SKIS control circuitry sends a valid key message to the Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus. If the response received identifies the key as invalid, or if no response is received from the key transponder, the SKIS sends an electronic invalid key message to the PCM.

The PCM will enable or disable engine operation based upon the status of the SKIS messages. It is important to note that the default condition in the PCM is an invalid key; therefore, if no message is received from the SKIS by the PCM, the engine will be disabled and the vehicle immobilized after two seconds of running.

The SKIS performs a self-test each time the status of the ignition transitions to On, and will store fault information in the form of a Diagnostic Trouble Code (DTC) in BCM memory if a system malfunction is detected. The Sentry Key antenna can be diagnosed, and any stored DTC can be retrieved using a diagnostic scan tool. Refer to the appropriate diagnostic information.