Dodge Dakota Sport 2001 Service Manual page 569

8Q - 8 VEHICLE THEFT SECURITY
TRANSPONDER KEY (Continued)
molded within a plastic mount into the head of the
metal key. In addition to being cut to match the
mechanical coding of the ignition lock cylinder, each
new Sentry Key has a unique transponder identifica-
tion code permanently programmed into it by the
manufacturer. The Sentry Key transponder cannot be
adjusted or repaired. If faulty or damaged, the entire
key must be replaced.
OPERATION
When the ignition switch is turned to the On posi-
tion, the Sentry Key Immobilizer Module (SKIM)
communicates through its antenna with the Sentry
Key transponder using a Radio Frequency (RF) sig-
nal. The SKIM then listens for a RF response from
the transponder through the same antenna. The Sen-
try Key transponder chip is within the range of the
SKIM transceiver antenna ring when it is inserted
into the ignition lock cylinder. The SKIM determines
whether a valid key is present in the ignition lock
cylinder based upon the response from the transpon-
der. If a valid key is detected, that fact is communi-
cated by the SKIM to the Powertrain Control Module
(PCM) over the Programmable Communications
Interface (PCI) data bus, and the PCM allows the
engine to continue running. If the PCM receives an
invalid key message, or receives no message from the
SKIM over the PCI data bus, the engine will be dis-
abled after about two seconds of operation. The Elec-
troMechanical Instrument Cluster (EMIC) will also
respond to the invalid key message on the PCI data
bus by flashing the security indicator on and off.
Each Sentry Key has a unique transponder identi-
fication code permanently programmed into it by the
manufacturer. Likewise, the SKIM has a unique
Secret Key code programmed into it by the manufac-
turer. When a Sentry Key is programmed into the
memory of the SKIM, the SKIM stores the transpon-
der identification code from the Sentry Key, and the
Sentry Key learns the Secret Key code from the
SKIM. Once the Sentry Key learns the Secret Key
code of the SKIM, it is permanently stored in the
memory of the transponder. Therefore, once a Sentry
Key has been programmed to a particular vehicle, it
cannot be used on any other vehicle. (Refer to 8 -
ELECTRICAL/VEHICLE
STANDARD PROCEDURE - TRANSPONDER PRO-
GRAMMING).
The SKIS performs a self-test each time the igni-
tion switch is turned to the On position, and will
store key-related fault information in the form of
Diagnostic Trouble Codes (DTC's) in SKIM memory if
a Sentry Key transponder problem is detected. The
Sentry Key transponder chip can be diagnosed, and
any stored DTC's can be retrieved using a DRBIII
scan tool. Refer to the appropriate diagnostic
information.
AN
THEFT SECURITY -