Sentry Key Immobilizer System
The Sentry Key Immobilizer System (SKIS) is designed to provide passive protection against unauthorized vehicle use by disabling the engine after about two seconds of running whenever an attempt is made to operate the vehicle using anything other than a key or FOB with Integrated Key (FOBIK) equipped with a valid Sentry Key transponder microchip. The SKIS is considered a passive protection system because it is always active when the ignition system is energized and does not require any customer intervention.
The Radio Frequency Hub Module (RFHM) (also known as the RF Hub) uses Radio Frequency (RF) communication to challenge and obtain confirmation that the FOBIK being used is valid for operating the vehicle. The microcontroller-based RFHM hardware and software also uses electronic messages to communicate with the ignition switch (also known as the Keyless Ignition Node (KIN) or IGnition Node Module/IGNM) over a private serial bus and with other electronic modules in the vehicle over the Controller Area Network (CAN) data bus. Refer to COMMUNICATION, OPERATION .
Pre-programmed Sentry Key transponder-equipped keys or FOBIK units are provided with the vehicle from the factory. Each RFHM will recognize a maximum of eight Sentry Key FOBIK units. If the customer would like additional Sentry Key FOBIK units other than those provided with the vehicle, they may be purchased from any authorized dealer. These additional FOBIK units must be programmed to the RFHM in the vehicle in order for the system to recognize them as valid. This can be done by the dealer using a diagnostic scan tool.
The RFHM performs a self-test of the SKIS each time the status of the ignition switch transitions to ON, and will store fault information in the form of a Diagnostic Trouble Code (DTC) for any system or component malfunction that is detected. If a fault is detected, the RFHM will send an electronic security indicator request message to the Instrument Cluster (IC) (also known as the Common Instrument Cluster/CIC) and the IC will illuminate the security indicator as appropriate.
The hard wired circuits between components related to the SKIS may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.
However, 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.