Sentry Key Immobilizer System (Skis)

The Sentry Key Immobilizer System (SKIS) uses Radio Frequency (RF) signals that are transmitted and received by the Sentry Key Immobilizer Module (SKIM) though a plastic ring that surrounds the lock cylinder. See Figure . The SKIM uses RF signals to communicate with special Sentry Key transponder keys. Each SKIM is programmed with a unique "Secret Key" code and security code. The SKIM sends the "Secret Key" code over the PCI bus line to the PCM. The PCM also stores the "Secret Key" code. The SKIM sends the "Secret Key" code to each Sentry Key transponder keys (up to 8 keys). The SKIM also stores the VIN in memory from PCM during initialization.

When ignition switch is turned to ON or START position, SKIM transmits an RF signal to energize the Sentry Key transponder key. If SKIM receives a valid "Secret Key" and transponder identification code, the SKIM sends an "Valid Key" message to PCM. PCM will allow engine start and run operations. If an invalid ignition key is used, SKIM will send invalid signal to PCM, causing engine to start and run for 2 seconds, then stop. If vehicle is started with invalid keys 6 times in a row, vehicle will shut down until correct key is used.

SKIM can also control operation of Vehicle Theft Security System (VTSS) LED by sending messages to BCM. BCM then controls VTSS LED.