Sentry Key Immobilizer System (SKIS) Overview

The Sentry Key Immobilizer System (SKIS) is designed to prevent unauthorized vehicle operation. The system consists of a Sentry Key Immobilizer Module (SKIM), ignition key(s) equipped with a transponder chip and PCM. When the ignition switch is turned on, the SKIM interrogates the ignition key. If the ignition key is Valid or Invalid, the SKIM sends a PCI Bus message to the Powertrain Control Module (PCM) indicating ignition key status. Upon receiving this message the PCM will terminate engine operation, or allow the engine to continue to operate.

The SKIM sends messages to the instrument cluster over the PCI bus to control the VTSS indicator lamp. The SKIM sends a message to the instrument cluster 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 the SKIM will flash the VTSS indicator lamp on and off.