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 any method other than a valid Sentry Key is used to start the vehicle. 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 SKIS uses Radio Frequency (RF) communication to obtain confirmation that the key in the ignition switch is a valid key for operating the vehicle. The microprocessor-based SKIS hardware and software also uses electronic messages to communicate with other electronic modules in the vehicle over the Controller Area Network (CAN) data bus. Refer to OPERATION .
Pre-programmed Sentry Key transponders are provided with the vehicle from the factory. Each Sentry Key Remote Entry Module (SKREEM) (also known as the Wireless Control Module/WCM) will recognize a maximum of eight Sentry Keys. If the customer would like additional keys other than those provided with the vehicle, they may be purchased from any authorized dealer. These additional keys must be programmed to the SKREEM in the vehicle in order for the system to recognize them as valid keys. This can be done by the dealer using a diagnostic scan tool or, if Customer Learn programming is an available SKIS feature in the market where the vehicle was purchased, the customer can program the additional keys, as long as at least two valid Sentry Keys are already available. See STANDARD PROCEDURE .
In vehicles equipped with an export premium version of the VTA, the SKIS also controls an electronic shaft lock module on the steering column that locks the steering shaft from rotation unless a valid key is detected in the ignition lock cylinder. The SKREEM communicates with the shaft lock module over a dedicated serial bus to monitor and control the shaft lock function.
The SKREEM performs a self-test of the SKIS and the shaft lock module each time the ignition switch is turned to the ON position, and will store fault information in the form of a Diagnostic Trouble Code (DTC) if a system malfunction is detected. The SKREEM will also send an electronic message to the instrument cluster if a fault is detected, and the instrument cluster illuminates the security indicator or displays a textual SHAFT LOCK ERROR message in the reconfigurable dot matrix display of the Electromechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) 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 or 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.