Sentry Key Immobilizer System (SKIS)

SENTRY KEY IMMOBILIZER SYSTEM (SKIS)
The SKIS is an immobilizer system designed to prevent unauthorized vehicle operation. The system consists of a Sentry Key Immobilizer Module (SKIM) and ignition key(s) called Sentry Key(s) which are equipped with a transponder chip. The SKIM communicates over the Chrysler Collision Detection (CCD) data bus network to the Powertrain Control Module (PCM), Body Control Module and/or the DRB scan tool.

When the ignition is turned to the Run/Start position, the SKIM produces a Radio Frequency (RF) via an antenna which is located around the ignition lock cylinder. The RF powers up the transponder chip inside the Sentry Key. The transponder chip then emits a coded signal that is received by the SKIM antenna. If this coded signal is valid, the SKIM sends a "Valid Key" message to the PCM. If the first transponder signal is not valid, the SKIM will attempt four more times to receive a correct transponder signal. If a valid signal is not received, the SKIM stores a diagnostic trouble code and sends an "Invalid Key" message to the PCM. Then the PCM will only allow the engine to start for two seconds then stall.

This start and stall will be allowed up to six times, after which the PCM will disable the starter relay.

The SKIS includes three valid Sentry Keys from the factory. If the customer wishes, additional Un-coded Sentry Key blanks are available. These blank keys must be cut to match a valid key, but the engine will not start unless the transponder chip inside the blank key is programmed to that particular vehicle.

The Sentry Key Immobilizer System (SKIS) can be programmed to recognize a total of eight keys.

The SKIM also sends messages to the body control module over the CCD bus to control the VTSS indicator lamp. The SKIM sends a message to the body control module to turn the lamp on for about three seconds when the ignition is turned to the Run/Start position as a bulb test. If the indicator lamp comes on and stays on after the bulb test, it indicates that the SKIM has detected a system malfunction and/or that the SKIS has become inoperative. If an invalid key is detected in the ignition key cylinder with the ignition switch in the Run/Start position, or when the SKIM has entered its customer key programming mode, the SKIM will flash the VTSS indicator lamp on and off.

Sentry Key Immobilizer Trouble Codes
Typically, modules have Diagnostic Trouble Codes that are referred to as either active or stored. In the case of the Sentry Key Immobilizer Module, however, all codes are stored codes. The two various types of stored codes in the SKIM can be considered to be either current or pre-existing codes. If more than one code exists, diagnostic priority should be given to the current code(s). A current code indicates a malfunction that is active at the time of vehicle service. A pre-existing code indicates the malfunction is not currently present. If a malfunction is not detected after 80 ignition cycles, it will automatically be erased.

VEHICLE THEFT SECURITY SYSTEM
This passive system is designed to protect against vehicle theft. The vehicle theft security system (VTSS) module is a logic-controlled device (part of the body control module), that monitors vehicle doors, trunk key cylinder and ignition action for unauthorized operation. The alarm activates by sounding the horn, flashing the headlamps, courtesy and VTSS lamps and providing an engine "no-run" feature which is accomplished by the Sentry Key Immobilizer System.

Passive arming occurs upon normal vehicle exit by turning the ignition off, opening the driver's door, locking the doors with the power lock and closing the driver's door. Manual arming occurs by using the key to lock the doors after closing them. The indicator lamp in the cluster will flash fast for 15 seconds, showing that arming is in progress. If no monitored systems are activated during this period, the system will arm. If the trunk key cylinder switch is not seen by the system, the indicator lamp will remain steadily lit during the arming process, although the system will still arm. The indicator lamp blinks at a slow rate when the system is armed.

When something triggers the alarm, the system will signal for about 18 minutes. For the first three minutes the horn will sound, then the headlamps and courtesy lamps will continue to flash for another 15 minutes.

Tamper Alert - If the horn sounds three times when either front door is unlocked, it means the alarm was activated. Check the vehicle for tampering. The VTSS indicator lamp will also flash twice quickly to indicate a tamper condition has occurred.

Manual Override - The system will not arm if the doors are locked using the manual lock control.
To verify the system, proceed as follows:
1. Open the driver's door.
2. Remove the ignition key (but keep it in hand).
3. Lock the doors with the power lock switch.
4. Close the driver's door.

NOTE: IF THE VTSS INDICATOR LAMP FLASHED, THE SYSTEM IS OPERATIONAL AND VERIFIED. IF NOT, THERE MAY BE A PROBLEM WITH THE SYSTEM.

System initialization is accomplished by communication between the powertrain control module and the body control module using the DRB.

Arming/Disarming - Active arming occurs when the remote keyless entry transmitter is used to lock the vehicle doors, whether the doors are open or closed. If one or more doors are open, the arming sequence starts only after all doors are closed.

Passive disarming occurs upon normal vehicle entry (unlocking either front door with the key). This disarming also will halt the alarm once it has been activated.

Active disarming occurs when the RKE transmitter is used to unlock the vehicle doors. This disarming also will halt the alarm once it has been activated.

System Self-Tests - NOTE: System self-tests can be entered only with the DRB.

Upon entering diagnostics, the headlamps, courtesy lamps and VTSS lamp will begin flashing to verify their operation. In addition, the horn will sound twice. Removing the key from the ignition switch Will stop the lamps from flashing while keeping the system in diagnostics.

While in diagnostics mode, a horn pulse should occur at each of the following events, which indicate proper operation.

1. Beginning with all doors closed, open then close each door. The horn will sound when the door ajar switch closed, and then again when the switch opens. There must be a one second delay between closing and opening the switch.
2. Rotate the key in each door lock cylinder to unlock position. The horn will sound as the switch closes, and again when it opens. There must be a one second delay between changing switch states, or the horn will not sound.
3. Cycle the key to the ignition RUN position. A single horn pulse will indicate proper operation of the ignition input. This also will take the module out of the diagnostics mode.

For any of these tests, if the switch does not remain open or closed for at least one second, the horn will only sound once.

The lack of a horn pulse during any operation indicates either:
- A switch failure
- The lack of that input to the body control module
- A failure internal to the module
- A faulty horn system

Check for continuity at the switch. If this is good, check for an open or shorted wire between the switch and body control module. Also, check if the Powertrain Control Module (PCM) has been replaced recently.

NOTE: A PCM FROM A VEHICLE EQUIPPED WITH A VEHICLE THEFT SECURITY SYSTEM CANNOT BE USED IN A VEHICLE THAT IS NOT EQUIPPED WITH A VEHICLE THEFT SECURITY SYSTEM.

If the VTSS indicator lamp comes on after ignition ON and stay on, the CCD bus communication with the PCM possibly has been lost.