bilizer Module (SKIM) is placing the proper messages
on the PCI bus, and that the Powertrain Control
Module (PCM) is receiving the PCI bus messages.
Refer to the proper Body Diagnostic Procedures man-
ual, and Wiring Diagrams for complete circuit
descriptions and diagrams.
(1) Check the fuses in the junction block. If OK, go
to Step 2. If not OK, repair the shorted circuit or
component as required and replace the faulty fuse.
(2) Disconnect and isolate the battery negative
remote cable from the remote terminal. Unplug the
wire harness connector at the SKIM. Check for con-
tinuity between the ground circuit cavity of the
SKIM wire harness connector and a good ground.
There should be continuity. If OK, go to Step 3. If not
OK, repair the open circuit to ground as required.
(3) Connect the battery negative cable. Check for
battery voltage at the fused B(+) circuit cavity of the
SKIM wire harness connector. If OK, go to Step 4. If
not OK, repair the open circuit to the fuse in the
junction block as required.
(4) Turn the ignition switch to the ON position.
Check for battery voltage at the fused ignition switch
output (run/start) circuit cavity of the SKIM wire
harness connector. If OK, use a DRB III
t scan tool
and the proper Body Diagnostic Procedures manual
to complete the diagnosis of the SKIS. If not OK,
repair the open circuit to the fuse in the junction
block as required.
DIAGNOSIS AND TESTING - VEHICLE THEFT
SECURITY SYSTEM
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, further details
on wire harness routing and retention, as well as
pin-out and location views for the various wire har-
ness connectors, splices and grounds. Using a DRB
III
t scan tool. Refer to the proper Body Diagnostic
Procedures Manual for test procedures.
TRANSPONDER KEY
DESCRIPTION
The Sentry Key Immobilizer System (SKIS) uses a
transponder chip that is integral to each ignition key
(Fig. 1) to communicate with the Sentry Key Immo-
bilizer Module (SKIM). Ignition keys are supplied
with the vehicle when it is shipped from the factory.
The transponder chip is undermolded within the
head of the key. This undermold is hidden beneath
an overmolded rubber cap.
OPERATION
Each Sentry Key has a unique transponder identi-
fication code permanently programmed into it by the
manufacturer. Likewise, the SKIM has a unique
9Secret Key9 code programmed into it by the manu-
facturer as well. When a Sentry Key is programmed
into the memory of the SKIM, the SKIM stores the
transponder identification code from the Sentry Key,
and the Sentry Key learns the
9Secret Key9 code from
the SKIM. Once the Sentry Key learns the
9Secret
Key
9 code of the SKIM, it is also permanently pro-
grammed into the transponder’s memory. Therefore,
blank keys for the SKIS must be programmed by the
SKIM in addition to being cut to match the mechan-
ical coding of the ignition lock cylinder. Refer to Elec-
trical,
Vehicle
Theft
Security,
Transponder
Key,
Standard Procedure - Transponder Programming.
The Sentry Key’s transponder is within the range
of the SKIM’s transceiver antenna ring when it is
inserted into the ignition lock cylinder. When the
ignition switch is turned to the ON position, the
SKIM communicates with the Sentry Key via a radio
frequency (RF) signal. The SKIM determines if a
valid key is present based on the information it
receives from the Sentry Key. If a valid key is
detected, that fact is communicated to the PCM via
the PCI bus and the vehicle is allowed to continue
running. If an invalid key is received by the PCM or
no status at all is communicated, the vehicle will
stall after two (2) seconds of running. The LED indi-
cator will be flashing at this point. The Sentry Key’s
transponder can not be repaired. If it is faulty or
damaged, it must be replaced.
Fig. 1 TRANSPONDER KEY - TYPICAL
1 - MOLDED CAP
2 - TRANSPONDER
3 - MOLDED CAP REMOVED
4 - SENTRY KEY
JR
VEHICLE THEFT SECURITY
8Q - 3
VEHICLE THEFT SECURITY (Continued)