Vehicle Theft Security System (Vtss)

Fig.1 Sentry Key Immobiliser System:

VEHICLE THEFT SECURITY SYSTEM
The Sentry Key Immobilizer System (SKIS) is available as a factory-installed option on this model. Vehicles equipped with this option can be readily identified by the presence of an amber SKIS indicator in the instrument cluster that will illuminate for about three seconds each time the ignition switch is turned to the ON position, or by a gray molded rubber cap on the head of the ignition key. Models not equipped with SKIS still have a SKIS indicator in the cluster, but it will not illuminate when the ignition switch is turned to the ON position. Also, models not equipped with the SKIS have a black molded rubber cap on the head of the ignition key.

The SKIS includes the following major components, which are described in further detail elsewhere:
- Powertrain Control Module (PCM) - The PCM is located on the left inner fender shield, ahead of the left front wheelhouse in the engine compartment.
- Sentry Key Immobilizer Module (SKIM) - The SKIM is located on the steering column near the ignition lock cylinder housing and an integral molded plastic antenna ring circles the ignition lock cylinder like a halo. The SKIM and its antenna are concealed beneath the steering column shrouds.
- Sentry Key Transponder - The Sentry Key transponder is molded into the head of the ignition key, and concealed by a gray molded rubber cap.
- SKIS Indicator - The SKIS indicator is located in the upper left corner of the instrument cluster overlay.

Except for the Sentry Key transponders, which rely upon Radio Frequency (RF) communication, hardwired circuitry connects the 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.

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 Chrysler Collision Detection (CCD) data bus (Refer to ELECTRONIC CONTROL MODULES/COMMUNICATION - OPERATION).

Pre-programmed Sentry Key transponders are provided with the vehicle from the factory. Each Sentry Key Immobilizer Module (SKIM) 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 SKIM in the vehicle in order for the system to recognize them as valid keys. This can be done by the dealer using a DRB III 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. (Refer to VEHICLE THEFT SECURITY - STANDARD PROCEDURE - SENTRY KEY TRANSPONDER PROGRAMMING).

The SKIS performs a self-test each time the ignition switch is turned to the ON position, and will store fault information in the form of Diagnostic Trouble Codes (DTC's) if a system malfunction is detected. The SKIS can be diagnosed, and any stored DTC's can be retrieved using a DRB III scan tool. Refer to the appropriate diagnostic information.

SKIS INDICATOR LAMP
A Sentry Key Immobilizer System (SKIS) indicator lamp is standard equipment on all instrument clusters, but is only functional on vehicles equipped with the optional SKIS. The SKIS indicator lamp is located near the upper edge of the instrument cluster overlay, in the upper left quadrant of the cluster. The SKIS indicator consists of a stenciled cutout of a graphical representation or icon of a key that is circled and crossed-out in the opaque layer of the instrument cluster overlay. The dark outer layer of the cluster overlay prevents the icon from being clearly visible when the lamp is not illuminated. However, an amber lens behind the cutout in the opaque layer of the cluster overlay causes the icon to appear in amber through the translucent outer layer of the overlay when it is illuminated from behind by a replaceable incandescent bulb and bulb holder unit located on the instrument cluster electronic circuit board. The SKIS indicator lamp is serviced as a unit with the instrument cluster.

The Sentry Key Immobilizer System (SKIS) indicator lamp gives an indication to the vehicle operator of the status of the SKIS. This lamp is controlled by the instrument cluster circuit board based upon electronic messages received by the cluster from the Sentry Key Immobilizer Module (SKIM) over the Chrysler Collision Detection (CCD) data bus. The SKIS indicator lamp bulb receives battery current on the instrument cluster electronic circuit board through the fused ignition switch output (st-run) circuit whenever the ignition switch is in the ON or Start positions; therefore, the lamp will always be OFF when the ignition switch is in any position except ON or Start. The lamp bulb only illuminates when it is switched to ground by the instrument cluster circuitry. The instrument cluster will turn ON the SKIS indicator lamp for the following reasons:
- Bulb Test - Each time the ignition switch is turned to the ON position, the SKIM tells the cluster to illuminate the lamp for about three seconds.
- SKIM Lamp-ON Message - Each time the cluster receives a lamp-ON message from the SKIM, the lamp will be illuminated. The lamp can be flashed ON and OFF, or illuminated solid, as dictated by the SKIM message. For more information on the SKIS and the SKIS lamp control parameters, (Refer to VEHICLE THEFT SECURITY - OPERATION). The lamp remains illuminated until the cluster receives a lamp-OFF message from the SKIM or until the ignition switch is turned to the OFF position, whichever occurs first.
- Actuator Test - Each time the cluster is put through the actuator test, the lamp will be turned ON and OFF in a prescribed sequence to confirm the functionality of the lamp and the cluster circuitry.

The SKIM performs a self-test each time the ignition switch is turned to the ON position to decide whether the system is in good operating condition. The SKIM then sends the proper SKIS lamp-ON or lamp-OFF messages to the instrument cluster. If the SKIS indicator lamp fails to light during the bulb test, replace the bulb with a known good unit. For further diagnosis of the SKIS indicator lamp or the instrument cluster circuitry that controls the lamp, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). If the instrument cluster turns ON the SKIS indicator lamp after the bulb test, either solid or flashing, it indicates that a SKIS malfunction has occurred or that the SKIS is inoperative. For proper diagnosis of the SKIS, the CCD data bus, or the message inputs to the instrument cluster that control the SKIS indicator lamp, a DRB III scan tool and the appropriate diagnostic information are required.

Sentry Key Immobilizer Transponder:

TRANSPONDER KEY
Each ignition key used in the Sentry Key Immobilizer System (SKIS) has an integral transponder chip. Ignition keys with this feature can be readily identified by a gray rubber cap molded onto the head of the key, while conventional ignition have a black molded rubber cap. The transponder chip is concealed beneath the molded rubber cap where it is molded within a plastic mount into the head of the metal key. In addition to being cut to match the mechanical coding of the ignition lock cylinder, each new Sentry Key has a unique transponder identification code permanently programmed into it by the manufacturer. The Sentry Key transponder cannot be adjuster or repaired. If faulty or damaged, the entire key must be replaced.

When the ignition switch is turned to the ON position, the Sentry Key Immobilizer Module (SKIM) communicates through its antenna with the Sentry Key transponder using a Radio Frequency (RF) signal. The SKIM then listens for a RF response from the transponder through the same antenna. The Sentry Key transponder chip is within the range of the SKIM transceiver antenna ring when it is inserted into the ignition lock cylinder. The SKIM determines whether a valid key is present in the ignition lock cylinder based upon the response from the transponder. If a valid key is detected, that fact is communicated by the SKIM to the Powertrain Control Module (PCM) over the Chrysler Collision Detection (CCD) data bus, and the PCM allows the engine to continue running. If the PCM receives an invalid key message, or receives no message from the SKIM over the CCD data bus, the engine will be disabled after about two seconds of operation. The ElectroMechanical Instrument Cluster (EMIC) will also respond to the invalid key message on the CCD data bus by flashing the SKIS indicator ON and OFF.

Each Sentry Key has a unique transponder identification code permanently programmed into it by the manufacturer. Likewise, the SKIM has a unique Secret Key code programmed into it by the manufacturer. when a Sentry Key is programmed into the memory of the SKIM, the SKIM stores the transponder identification code from the Sentry Key, and the Sentry Key learns the Secret Key code from the SKIM. Once the Sentry Key learns the Secret Key code of the SKIM, it is permanently stored in the memory of the transponder. Therefore, once a Sentry Key has been programmed to a particular vehicle, it cannot be used on any other vehicle. (Refer to VEHICLE THEFT SECURITY - STANDARD PROCEDURE - SENTRY KEY TRANSPONDER PROGRAMMING).

The SKIS performs a self-test each time the ignition switch is turned to the ON position, and will store key-related fault information in the form of Diagnostic Trouble Codes (DTC's) in SKIM memory if a Sentry Key transponder problem is detected. The Sentry Key transponder chip can be diagnosed, and any stored DTC's can be retrieved using a DRB III scan tool. Refer to the appropriate diagnostic information.