Description And Operation: Operation

When the status of the ignition switch (Keyless Ignition Node/KIN) transitions to ON, it sends an electronic ignition switch status  message over a dedicated Security K Local Interface Network (LIN) serial bus circuit to the Radio Frequency Hub (RFH). All vehicles are equipped with the PEKG system, therefore the RFH relies upon several Low Frequency (LF) antenna units to challenge the key transponders using a LF signal, then monitors responses from the key transponders received as Very High Frequency (VHF) signals. The RFH determines whether a valid FOBIK is present based upon the response from the transponder.

If a valid FOBIK is detected, it is communicated by the RFH to the Powertrain Control Module (PCM) over the Controller Area Network (CAN) data bus, and the PCM allows the engine to start. If the PCM receives an invalid key message, or receives no message from the RFH over the CAN data bus, the engine will not start. The Instrument Panel Cluster (IPC) will also respond to the invalid key message on the CAN data bus by displaying an error message in the Electronic Vehicle Information Center (EVIC).

Likewise, when any one of the RKE transmitter buttons of the FOBIK is depressed, the on-board transmitter of the FOBIK generates a high frequency Radio Frequency (RF) request signal that is received and validated by the RFH. If the RFH determines that the RKE transmitter RF request signal was generated by a FOBIK that is valid for the vehicle, the RFH relays electronic request messages to the appropriate electronic modules in the vehicle over the CAN data bus to invoke the functions or features associated with the request.

The dealer can generate a Personal Identification Number (PIN) at the time of service by connecting a scan tool to the vehicle and then to DealerCONNECT. This number is required along with a diagnostic scan tool for the dealer to program an additional or replacement FOBIK into the RFH as a valid key. The PIN expires in 12 hours, after which a new PIN will need to be generated if required for further service. The mechanical emergency key included with a new additional or replacement blank FOBIK must also be cut to match the coding of the lock cylinders in the vehicle.

Each FOBIK has a unique transponder identification code permanently programmed into it by the manufacturer. Likewise, the RFH has a unique Secret Key code programmed into it by the manufacturer. When a FOBIK is programmed into the memory of the RFH, the RFH stores the transponder identification code from the FOBIK, and the FOBIK learns the Secret Key code from the RFH. Once the FOBIK learns the Secret Key code of the RFH, it is permanently stored in the memory of the transponder. Therefore, once a FOBIK has been programmed to a particular vehicle, it cannot be used on any other vehicle. Refer to STANDARD PROCEDURE .

The Sentry Key Immobilizer System (SKIS) performs a self-test each time the ignition switch status transitions to ON, and will store key-related fault information in the form of a Diagnostic Trouble Code (DTC) in RFH memory if a key transponder problem is detected. The key transponder chip can be diagnosed, and any stored DTC can be retrieved using a diagnostic scan tool. Refer to the appropriate diagnostic information.

Common communication problems include:

• Two transponder keys too close to each other.
• Another transponder device (i.e.: Speed Pass) too close to the key transponder.
• Transponder too close to a cellular phone.
• A cellular phone charger in the vehicle causing interference.
• Cellular phone near keys metal objects.

Conventional diagnostic methods will not prove conclusive in the diagnosis of the SKIS or the electronic controls and communication between other modules and devices that provide some features of the SKIS. The most reliable, efficient and accurate means to diagnose the SKIS or the electronic controls and communication related to SKIS operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.