Certain criteria must be met for a diagnostic
trouble code to be entered into the SKIM memeory.
The criteria may be a range of; Input voltage, CCD
Bus message, or coded messages to the SKIM. If all
of the criteria for monitoring a circuit or function
are met and a fault is sensed, a diagnostic trouble
code will be stored in the SKIM memory.
3.2.8 SKIS OPERATION
When ignition power is supplied to the SKIM, the
SKIM performs an internal self-test. After the self-
test is completed, the SKIM neergizes the antenna
(this activates the transponder chop responds to the
challenge by generating an encrypted response
message using the following:
Secret Key -This is an electronically stored
value (identification number) that is unique to each
SKIS. The secret key is stored in the SKIM, PCM
and all ignition key tranponders.
Challenge -This is a random numbr that is
generated by the SKIM at each ignition key cycle.
The secret key and challenge are plugged into an
algorithm that produces the encrypted response
message. The transponder uses the crypto algo-
rithm to receive, decode and respond to the message
sent by the SKIM. After responding to the coded
message, the transponder sends a transponder ID
message to the SKIM. The SKIM compares the
transponder ID to the available valid key codes in
the SKIM memory (8 key maximum). After validat-
ing the key the SKIM sends a CCD Bus message
called a ``Seed Request'' to the engine controller
then waits for a PCM response. If the PCM does not
respond, the SKIM will send the seed request agian.
After three failed attempts the SKIM will stop
sending the seed request and store a trouble code. If
the PCM sends a seed response, the SKIM sends a
valid/invalid key message to the PCM. This is an
encrypted message that is generated using the
following:
VIN -Vehicle Identification Number
Seed -This is a random number that is generated
by the PCM at each ignition key cycle.
The VIN and seed are plugged into a rolling code
algorithm that encrypts the ``valid/invalid key'' mes-
sage. The PCM uses the rolling code algorithm to
receive, decode and respond to the valid/invalid key
message sent by the SKIM. After sending the valid/
invalid key massage the SKIM waits 3.5 seconds for
a PCM status message from the PCM. If the PCM
does not respond with a valid key message to the
SKIM, a fault is detected and a trouble code is
stored.
The SKIS incorporates a warning lamp (``ALARM
SET'') located in the message center. The lamp
receives switched ignition voltage and is hardwired
to the body control module. The lamp is actuated
when the SKIM sends a CCD Bus message to thebody controller requesting the lamp on. The body
controller then provides the ground for the lamp.
The SKIM will request lamp operation for the
following:
- bulb checks at ignition on
- to alert the vehicle operator to a SKIS malfunc-
tion
For all faults except transponder faults and VIN
mismatch, the lamp remains on steady. In the event
of a tranponder fault the light flashes at a rate of 1
Hz (once per second). If a fault is pesent the lamp
will emain on or flashing for the complete ignition
cycle. If a fault is stored in SKIM memory which
prevents the system form operating properly, the
PCM will allow the engine to start and run (for 2
seconds) up to six times. After the sixth attempt, the
PCM disables the starter relay until the fault is
corrected.
3.2.9 PROGRAMMING THE POWERTRAIN
CONTROL MODULE
Important Note:Before replacing the PCM for a
failed driver, control circuit or ground circuit, be
sure to check the related component/circuit integ-
rity for failures not detected due to a double fault in
the circuit. Most PCM driver/control circuit failures
are caused by internal failure to components (i.e.
12-volt pull-ups, drivers and ground sensors). These
failures are difficult to detect when a double fault
has occurred and only one DTC has set.
NOTE:IF THE PCM AND THE SKIM ARE
REPLACED AT THE SAME TIME, PROGRAM
THE VIN INTO THE PCM FIRST. ALL VEHICLE
KEYS WILL THEN NEED TO BE REPLACED
AND PROGRAMMED TO THE NEW SKIM.
The SKIS ``Secret Key'' is an ID code that is
unique to each SKIS. This code is programmed and
stored in the SKIM, engine controller and transpon-
der ship (ignition key). When replacing the PCM it
is necessary to program the secret key into the
PCM.
1. Turn the ignition on (transmission in park/
neutral).
2. Use the DRB and select ``THEFT ALARM'',
SKIM then MISCELLANEOUS''.
3. Select ``PCM REPLACED''.
4. Enter secured access mode by entering the vehi-
cle four-digit PIN.
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NOTE:IF THREE ATTEMPTS ARE MADE TO
ENTER THE SECURE ACCESS MODE USING
AN INCORRECT PIN, SECURED ACCESS
MODE WILL BE LOCKED OUT FOR ONE
HOUR. TO EXIT THIS LOCKOUT MODE, TURN
THE IGNITION TO THE RUN POSITION FOR
ONE HOUR THEN ENTER THE CORRECT
PIN. (ENSURE ALL ACCESSORIES ARE
TURNED OFF. ALSO MONITOR THE
BATTERY STATE AND CONNECT A BATTERY
CHARGER IF NECESSARY).
5. Press ``ENTER'' to transfer the secret key (the
SKIM will send the secret key to the PCM).
3.2.10 PROGRAMMING THE SENTRY KEY
IMMOBILIZER MODULE
NOTE:IF THE PCM AND THE SKIM ARE
REPLACED AT THE SAME TIME, PROGRAM
THE VIN INTO THE PCM FIRST. ALL VEHICLE
KEYS WILL THEN NEED TO BE REPLACED
AND PROGRAMMMED TO THE NEW SKIM.
1. Turn the ignition on (transmission in park/
neutral).
2. Use the DRB and select ``THEFT ALARM'',
``SKIM'' then MISCELLLANEOUS.
3. Select ``SKIM MOSULE REPLACEMENT (GAS-
OLINE)''
4. Program the vehicle four-digit PIN into the
SKIM.
5. Select ``COUNTRY CODE'' and enter the correct
country.
NOTE:BE SURE TO ENTER THE CORRECT
COUNTRY CODE. IF THE INCORRECT
COUNTRY CODE IS PROGRAMMED INTO
SKIM, THE SKIM MUST BE REPLACED.
6. Select ``UPDATE VIN'' (the SKIM will learn the
VIN from the PCM).
7. Press ``ENTER'' to transfer the VIN (the PCM
will send the VIN to the SKIM).
8. The DRB will ask if you want to transfer the
secret key. Select ``ENTER'' to transfer secret key
from the PCM. This will ensure the current
vehicle ignition keys will still operate the SKIS
system.
3.2.11 PROGRAMMING THE IGNITION
KEYS TO THE SENTRY KEY
IMMOBILIZER MODULE
1. Turn the ignition on (transmission in park/
neutral).2. Use the DRB and select ``THEFT ALARM'',
``SKIM'' then ``MISCELLANEOUS''.
3. Select ``PROGRAM IGNITION KEYS''.
4. Enter secured access mode by entering the vehi-
cle four-digit PIN.
NOTE:A MAXIMUM OF EIGHT KEYS CAN BE
LEARNED TO EACH SKIM. ONCE A KEY IS
LEARNED TO A SKIM IT (THE KEY) CANNOT
BE RANFERRED TO ANOTHER VEHICLE.
If ignition key programming is unsuccessful, the
DRB will display one of the following messages:
Programming Not Attempted -The DRB at-
tempts to read the programmed key status and
there are no keys programmmed in the SKIM
memory.
Programming Key Failed -(Possible Used Key
From Wrong Vehicle) - SKIM is unable to program
key due to one of the following:
- faulty ignition key transponder
- ignition key is programmed to another vehicle.
8 Keys Already Learned, Programming Not
Done -SKIM transponder ID memory is full.
1. Obtain ignition keys to be programmed from
customer (8 keys maximum)
2. Using the DRB, erase all ignition keys by select-
ing ``MISCELLANEOUS'' and ``ERASE ALL
CURRENT IGN. KEYS''
3. Program all ignition keys.
Learned Key In Ignition -Ignition key tran-
sponder ID is currently programmed in SKIM mem-
ory.
3.3 DIAGNOSTIC TROUBLE CODES
Each diagnostic trouble code is diagnosed by
following a specific testing procedure. The diagnos-
tic test procedures contain step-by-step instructions
for determining the cause of trouble codes as well as
no trouble code problems. It is not necessary to
perform all of the tests in this book to diagnose an
individual code.
Always begin by reading the diagnostic trouble
codes using the DRBIIIt.
3.3.1 HARD CODE
A diagnostic trouble code that comes back within
one cycle of the ignition key is a ªhardº code. This
means that the defect is there every time the
powertrain control module checks that circuit or
function. Procedures in this manual verify if the
trouble code is a hard code at a the beginning of
each test. When it is not a hard code, an ªintermit-
tentº test must be performed.
Codes that are for Euro Stage III OBD monitors will
not set with just the ignition key on. Comparing these
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