Security Lamp/Indicator: Description and Operation

The Sentry Key Immobilizer System (SKIS) uses an indicator light to convey information on the status of the system to the customer. This indicator is shared with the Vehicle Theft Security System (VTSS). The VTSS/SKIS indicator is a Light Emitting Diode (LED), and is not serviceable separately. The indicator is located in the Instrument Cluster.

The indicator is controlled by the Body Control Module (BCM) based upon messages it receives from the Sentry Key Immobilizer Module (SKIM) on the PCI bus.

When the ignition is turned ON, the Body Control Module (BCM) performs a four second bulb check, regardless of Sentry Key Immobilizer Module (SKIM) messages. After the bulb check, the indicator is controlled according to SKIM messages. Then, the SKIM sends messages to the BCM to operate the indicator based upon the results of the SKIS self tests. The indicator may be actuated in two possible ways, FLASHING or ON SOLID. If the indicator comes ON and stays ON solid after a power-up test, this indicates that the SKIM has detected a system malfunction. If the SKIM detects an invalid key when the ignition switch is moved to the ON position, it sends a message on the PCI bus to the BCM, to flash the indicator. The SKIM can also send a message to flash the indicator and generate a single audible chime at the same time. These two events occurring simultaneously indicate that the SKIS has been placed into the "Customer Learn" mode. If the indicator comes on and stays on after the power-up test, diagnosis of the SKIS should be performed using a DRB III(R) scan tool and the appropriate Body Diagnostic Procedures manual. The LED indicator is not a serviceable component and if found faulty or damaged, the entire instrument cluster must be replaced.