Jeep Cherokee 2000 Service Manual page 537

XJ
DESCRIPTION AND OPERATION (Continued)
The SKIM sends messages to the instrument clus-
ter 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 bus messages to keep the lamp off for a dura-
tion of about one second. Then the SKIM sends mes-
sages 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 or transponder fault when the
ignition switch is turned to the On position, it sends
messages to the instrument cluster to flash the SKIS
indicator lamp.
The SKIS indicator lamp uses a replaceable incan-
descent bulb and bulb holder on the instrument clus-
ter electronic circuit board. Refer to Group 8E -
Instrument Panel Systems for diagnosis and service
of a faulty SKIS indicator lamp. If the SKIS indicator
lamp comes on and stays on after the bulb test func-
tion, diagnosis of the SKIS should be performed with
a DRB scan tool and the proper Diagnostic Proce-
dures manual.
DIAGNOSIS AND TESTING
SENTRY KEY IMMOBILIZER SYSTEM
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
NOTE: The following tests may not prove conclu-
sive in the diagnosis of this system. The most reli-
able, efficient, and accurate means to diagnose the
Sentry Key Immobilizer System involves the use of
a DRB scan tool. Refer to the proper Diagnostic
Procedures manual for the procedures.
The Sentry Key Immobilizer System (SKIS) and
the Chrysler Collision Detection (CCD) data bus net-
GROUP 8M - PASSIVE
STEERING COLUMN,
VEHICLE THEFT/SECURITY SYSTEMS
work should be diagnosed using a DRB scan tool.
The DRB will allow confirmation that the CCD data
bus is functional, that the Sentry Key Immobilizer
Module (SKIM) is placing the proper messages on the
CCD data bus, and that the Powertrain Control Mod-
ule (PCM) and the instrument cluster are receiving
the CCD data bus messages. Refer to the proper
Diagnostic Procedures manual for the procedures.
Refer to 8W-30 - Fuel/Ignition System in Group 8W -
Wiring Diagrams for complete circuit descriptions
and diagrams.
(1) Check the fuses in the fuseblock module. 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
cable. Unplug the wire harness connector at the
SKIM. Check for continuity between the ground cir-
cuit 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
fuseblock module 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 scan tool and
the proper Diagnostic Procedures manual to complete
the diagnosis of the SKIS. If not OK, repair the open
circuit to the fuse in the fuseblock module as
required.
OR
SERVICE PROCEDURES
SENTRY KEY IMMOBILIZER SYSTEM
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
transponders, for a total of eight Sentry Keys. Sentry
Key programming will require the use of a DRB scan
tool and the proper Diagnostic Procedures manual.
recognize up to six
8Q - 3
additional