Grand Cherokee 4WD V8-4.7L VIN N (2000)
Security Lamp/Indicator: Description and Operation
SENTRY KEY IMMOBILIZER SYSTEM INDICATOR LAMP
The Sentry Key Immobilizer System (SKIS) indicator lamp gives an indication when the SKIS is faulty or when the vehicle has been immobilized
due to the use of an invalid ignition key. The lamp is controlled by the Electro-Mechanical Instrument Cluster (EMIC) circuitry based upon
messages received from the Sentry Key Immobilizer Module (SKIM) over the Programmable Communications Interface (PCI) data bus network.
The SKIS indicator lamp uses a replaceable incandescent bulb and bulb holder on the EMIC electronic circuit board. If the SKIS indicator lamp
comes on and stays on after the bulb test function, diagnosis of the SKIS and the PCI data bus should be performed with a DRB scan tool and the
proper Diagnostic Procedures.
The SKIM sends messages to the EMIC over the PCI data bus to turn the lamp on for about three seconds when the ignition switch is turned to the
On position as a bulb test. After completion of the bulb test, the SKIM sends PCI data bus messages to keep the lamp off for a duration of about
one second. Then the SKIM sends messages to the instrument cluster circuitry to turn the lamp on or off based upon the results of the SKIS
self-tests. If the SKIS 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 the SKIM detects an invalid key when the ignition switch is turned to the On position, it sends messages to the instrument cluster to flash the
SKIS indicator lamp. The SKIM can also send messages to the instrument cluster to flash the lamp and to the Body Control Module (BCM) to
generate a single audible chime tone. These functions serve as an indication to the customer that the SKIS has been placed in its "Customer Learn"
programming mode.
VEHICLE THEFT SECURITY SYSTEM INDICATOR LAMP
The Vehicle Theft Security System (VTSS) Light Emitting Diode (LED) is a red light-emitting diode that is integral to the auto headlamp light
sensor, which is mounted on top of the instrument panel near the driver side defroster outlet. The LED is connected to fused battery current at all
times and is hard wired to the Body Control Module (BCM) through the instrument panel wire harness.
The VTSS LED cannot be adjusted or repaired and, if faulty or damaged, auto headlamp light sensor/VTSS LED unit must be replaced. Refer to
Auto Headlamp Sensor in the Removal and Installation for the service procedures. For complete circuit diagrams.
The VTSS LED gives a visible indication of the VTSS arming status. One side of the LED is connected to battery current at all times. The other
side of the LED is hard wired to the BCM, which controls the operation of the LED by switching this side of the circuit to ground. When the
VTSS arming is in progress, the BCM will flash the LED rapidly on and off for about fifteen seconds. When the VTSS has been successfully
armed, the BCM will flash the LED on and off continually at a much slower rate until the VTSS is disarmed.
