OPERATION
Each Sentry Key transponder has a unique tran-
sponder 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 identifica-
tion 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. See
Sentry Key Immobilizer System Transponder Pro-
gramming in this section 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 igni-
tion switch is turned to the START or ON positions,
the SKIM transceiver issues a Radio Frequency (RF)
signal that excites the transponder chip. The tran-
sponder chip responds by issuing an RF signal con-
taining 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.
The Sentry Key transponder cannot be repaired
and, if faulty or damaged, it must be replaced.
STANDARD PROCEDURE - TRANSPONDER
PROGRAMMING
Two programmed sentry key transponders are
included with the Sentry Key Immobilizer System
(SKIS) when it is shipped from the factory. The Sen-
try Key Immobilizer Module (SKIM) can be pro-
grammed
to
recognize
up
to
six
additional
transponders, for a total of eight Sentry Keys. The
following “Customer Learn” programming procedure
for the programming of additional transponders
requires access to at least two of the valid Sentry
Keys. If two valid Sentry Keys are not available, Sen-
try Key programming will require the use of a DRB
III
t scan tool and the proper Body Diagnostic Proce-
dures Manual.
CUSTOMER LEARN
(1) Obtain the additional Sentry Key transponder
blank(s) that are to be programmed for the vehicle.
Cut the additional Sentry Key transponder blanks to
match the ignition lock cylinder mechanical key
codes.
(2) Insert one of the two valid Sentry Key tran-
sponders into the ignition switch and turn the igni-
tion switch to the ON position.
(3) After the ignition switch has been in the ON
position for about three seconds, but no more than
fifteen seconds, cycle the ignition switch back to the
OFF position. Replace the first valid Sentry Key in
the ignition lock cylinder with the second valid Sen-
try Key and turn the ignition switch back to the ON
position. Both operations must be performed within
15 seconds.
(4) About ten seconds after the completion of Step
3, the VTSS indicator LED will start to flash and a
single audible chime tone will sound to indicate that
the system has entered the “Customer Learn” pro-
gramming mode.
(5) Within about fifty seconds of entering the “Cus-
tomer Learn” programming mode, turn the ignition
switch to the OFF position, replace the valid Sentry
Key with a blank Sentry Key transponder, and turn
the ignition switch back to the ON position.
(6) About ten seconds after the completion of Step
5, a single audible chime tone will sound and the
VTSS indicator LED will stop flashing and stay on
solid for about three seconds to indicate that the
blank Sentry Key transponder has been successfully
programmed. The SKIS will immediately return to
normal system operation following exit from the
“Customer Learn” programming mode.
(7) Go back to Step 2 and repeat this process for
each additional Sentry Key transponder blank to be
programmed.
If any of the above steps is not completed in the
proper sequence, or within the allotted time, the
SKIS will automatically exit the “Customer Learn”
programming mode. The SKIS will also automatically
exit the “Customer Learn” programming mode if it
sees a non-blank Sentry Key transponder when it
should see a blank, if it has already programmed
eight valid Sentry Keys, or if the ignition switch is
turned to the OFF position for more than about fifty
seconds.
VTSS INDICATOR
DESCRIPTION
The Sentry Key Immobilizer System (SKIS) uses
the Vehicle Theft Security System (VTSS) indicator
LED to give an indication when the SKIS is faulty or
when the vehicle has been immobilized due to the
use of an invalid ignition key. The LED is controlled
by the BCM based upon messages received from the
Sentry Key Immobilizer Module (SKIM). The VTSS/
SKIS indicator LED is hard wired directly to the
BCM.
LH
VEHICLE THEFT SECURITY
8Q - 5
TRANSPONDER KEY (Continued)