Sentry Key Immobilizer System: Notes

SENTRY KEY IMMOBILIZER SYSTEM 

Courtesy of CHRYSLER GROUP, LLC

The SKIS includes the following major components:

1.	Refer to POWERTRAIN CONTROL MODULE .
2.	Refer to BODY CONTROL MODULE .
3.	Refer to INSTRUMENT PANEL CLUSTER  (Security Indicator).
4.	Refer to IGNITION NODE MODULE . Refer to SENTRY KEY ANTENNA . Refer to KEYLESS IGNITION NODE .
5.	Refer to LOW FREQUENCY ANTENNA .
6.	Refer to RADIO FREQUENCY HUB .
7.	Refer to SENTRY KEY TRANSPONDER .

In vehicles not equipped with the optional Passive Entry Keyless Go (PEKG) system, the SKIS is integral to the BCM. In vehicles equipped with the optional PEKG system, the SKIS is integral to the RFHM.

The SKIS is factory-installed standard equipment on this vehicle. The SKIS provides passive vehicle protection, immobilizing the vehicle by preventing the engine from operating unless a valid electronically encoded key or Frequency Operated Button with Integrated Key (FOBIK) is detected. In vehicles not equipped with the optional Passive Entry Keyless Go (PEKG) system the valid key must be present in the ignition lock cylinder. In vehicles equipped with the PEKG system, a valid FOBIK must only be present somewhere inside the passenger compartment of the vehicle for the engine to operate. Vehicles with this equipment can be readily identified by the illumination of the security indicator in the IPC for about three seconds after the status of the ignition transitions to ON as a SKIS bulb test.

The BCM, the PCM and the RFH each contain a microcontroller and programming that allow them to communicate with each other and other electronic modules in the vehicle using the Controller Area Network (CAN) C data bus. In addition, in vehicles so equipped, the KIN and the RFH communicate with each other using a Security K-line data bus. Refer to COMMUNICATION, DESCRIPTION AND OPERATION .

Except for the Sentry Key transponders, which rely upon Radio Frequency (RF) communication, hard wired circuitry connects the various SKIS components to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the SKIS components through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin out and location views for the various wire harness connectors, splices and grounds.

OPERATION 

The 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 or FOBIK is used to attempt starting 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.

In vehicles without the optional PEKG system the SKIS uses Radio Frequency (RF) communication to obtain confirmation that the key in the ignition switch lock cylinder is a valid key for operating the vehicle. In vehicles with the optional PEKG system the SKIS uses Low Frequency (LF) RF communication to obtain confirmation that the FOBIK within the passenger compartment is valid for operating the vehicle.

In vehicles without the optional PEKG system the microcontroller-based BCM contains the SKIS software. The BCM monitors a hard wired input from the Sentry Key antenna. In vehicles with the optional PEKG system the microcontroller-based RFH uses electronic messages over a dedicated Security K-line data bus to communicate with the KIN. In both systems the BCM or the RFH also use electronic messages to communicate with other electronic modules in the vehicle over the CAN-C data bus. Refer to COMMUNICATION, DESCRIPTION AND OPERATION .

If the car has keys with a mechanical groove, the key identifiers are stored in the BCM. When the vehicle user turns the ignition switch to "ON," the relay that distributes the ignition-operated B(+) is activated and the instrument panel switches on. At this point the secret code request (IMMO CODE REQUEST) leaves the PCM for the BCM. This energizes the key transponder through the antenna in the ignition switch and reads the key ID information and the secret code. If the key is recognized as "valid," the BCM responds to the PCM's request (IMMO CODE RESPONSE), thus initiating the encrypted (mini-crypt) dialogue with the PCM. At the end of the dialogue between BCM and PCM, if the outcome is positive, the PCM will allow the engine to be started. If the outcome is negative, the PCM will not enable engine starting. In this case, the BCM will send a request to the IPC to switch on the Code Immobilizer warning light.

If the vehicle has FOBIK keys, the key identifiers are stored in the RFH. When the vehicle user presses the KIN and Start/Stop module, this sends the RFH (via the Security K-line data bus and the analogue "redundant run" signal) the information that the button has been pressed. At this point, the RFH communicates to the BCM that the button has been pressed. The BCM, in turn, will send a request to the RFH to read and identify the FOBIK identifier. If the RFH recognizes the FOBIK (inside the vehicle) as a "valid FOBIK," it sends this information to the BCM, which in turn sends a request to the Electric Steering-column Lock (ESL) module to release the steering column (if equipped). After release, the ESL will send confirmation to the BCM, which will activate the relay that distributes the +15 supplies (the panel switches on). With the +15, the encrypted (mini-crypt) dialogue between BCM and PCM is triggered: the PCM sends a secret code request (IMMO CODE REQUEST) to the +15 for the BCM, which will respond to the request (IMMO CODE RESPONSE). If the outcome of the dialogue is positive, the PCM will permit the engine to be started. If the outcome is negative, the PCM will not enable engine starting. In this case, the BCM will send a request to the IPC to turn on the Code Immobilizer warning light.

The BCM or the RFH performs a self-test of the SKIS each time the status of the ignition transitions out of Off and will store fault information in the form of a Diagnostic Trouble Code (DTC) if a system malfunction is detected. The BCM or the RFHM will also send an electronic message to the IPC if a fault is detected. The IPC responds by illuminating the security indicator or displaying a textual message in the Electronic Vehicle Information Center (EVIC) display.

The hardwired 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.

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.