Grand Cherokee 2WD V8-4.7L VIN N (2000)
Alarm System Transponder: Description and Operation
Sentry Key Immobilizer Transponder
The Sentry Key Immobilizer System (SKIS) uses a transponder that is integral to each of the two ignition keys that are supplied with the vehicle when it
is shipped from the factory. The transponder chip is insulated within a nylon mount inserted in the head of the key, and invisible beneath a molded rubber
cap. For ease of identification, the molded rubber cap of ignition keys with a transponder are gray in color, while ignition keys without a transponder
have a black cap.The Sentry Key transponder cannot be repaired and, if faulty or damaged, it must be replaced.
Each Sentry Key transponder has a unique transponder identification code programmed into it by the manufacturer. The Sentry Key Immobilizer Module
(SKIM) has a unique "Secret Key" code programmed into it by the manufacturer. When a Sentry Key transponder is programmed into the memory of
the SKIM, the SKIM learns the transponder identification code from the transponder, and the transponder learns the "Secret Key" code from the SKIM.
Each of these codes is stored within the transponder and in the nonvolatile memory of the SKIM. Therefore, blank keys for the SKIS must be
programmed by and into the SKIM, in addition to being cut to match the mechanical coding of the ignition lock cylinder. Refer to Sentry Key
Immobilizer System Transponder Programming in the Service Procedures for more information.The Sentry Key transponder is within the range of the
SKIM transceiver antenna ring when it is inserted in the ignition lock cylinder. When the ignition switch is turned to the Start or On positions, the SKIM
transceiver issues a Radio Frequency (RF) signal that excites the transponder chip. The transponder chip responds by issuing an RF signal containing its
transponder identification code and the "Secret Key" code. The SKIM transceiver compares the transponder codes with the codes stored in its memory to
determine whether a valid key is in the ignition lock cylinder.
