Functional Description

SENTRY KEY IMMOBILIZER
The SKIS is an immobilizer system designed to prevent unauthorized vehicle operation. The system consists of a Sentry Key Immobilizer Module (SKIM) and ignition key(s) called Sentry Key(s) which are equipped with a transponder chip. The SKIM communicates over the Chrysler Collision Detection Multiplex System (CCD) bus network to the Powertrain Control Module (PCM), and/or the DRB scan tool.

When the ignition is turned to the Run/Start position, the SKIM produces a Radio Frequency (RF) signal via an antenna which is located around the ignition lock cylinder. The RF powers up the transponder chip inside the Sentry Key. The transponder chip then emits a coded signal that is received by the SKIM antenna. If this coded signal is valid, the SKIM sends a "VALID KEY" message to the PCM. If the first transponder signal is not valid, the SKIM will attempt four more times to receive a correct transponder signal. If a valid signal is not received, the SKIM stores a diagnostic trouble code and send a "INVALID KEY" message to the PCM. Then the PCM will only allow the engine to start for two seconds then stall. This start and stall will be allowed up to six times, after which the PCM will disable the starter relay.

The SKIS includes two valid Sentry Keys from the factory. If the customer wishes, additional uncoded Sentry Key blanks are available. These blank keys must be cut to match a valid key, but the engine Will not start unless the transponder chip inside the blank key is programmed to that particular vehicle.

The Sentry Key Immobilizer System (SKIS) can be programmed to recognize a total of eight keys.

The SKIM sends messages to the Instrument Cluster over the CCD bus to control the SKIM indicator lamp. The SKIM sends a message to the cluster for about three seconds when the ignition is turned to the Run/Start position as a bulb test. If the indicator lamp comes ON and stays ON after the bulb test, it indicates that the SKIM has detected a system malfunction and/or that SKIS has become inoperative. If an invalid key is detected in the ignition key cylinder with the ignition switch in the Run/Start position, or when the SKIM has entered its customer key programming mode, the SKIM will flash the SKIM indicator lamp ON and OFF.

Sentry Key Immobilizer Trouble Codes
Typically, modules have Diagnostic Trouble Codes that are referred to as either active or stored. In the case of the Sentry Key Immobilizer Module, however, all codes are stored codes. The two various types of stored codes in the SKIM can be considered to be either current or pre-existing codes. If more than one code exists, diagnostic priority should be given to the active code(s). Record the DTC's before attempting to erase the DTC's. Active codes cannot be erased. Cycle the ignition and wait 90 seconds before reading DTC's again. If there are no active DTC's then refer to the pre-existing DTC's recorded in the previous step. A current code indicates a malfunction that is CURRENT at the time of vehicle service. A pre-existing code indicates the malfunction is not currently present. If a malfunction is not detected after 80 ignition cycles, the code will automatically be erased.

Sentry Key Immobilizer Module Trouble Codes
Antenna Failure
EEPROM Failure
Internal SKIM Failure
PCM Status Failure
Rolling Code Failure
Serial Link External Failure
Serial Link Internal Failure
Transponder Communication Failure
Transponder (Cyclic Redundancy Check) CRC Failure
Transponder ID Mismatched
Transponder Response Mismatch VIN Mismatch

Sentry Key Immobilizer Module Replacement And System Initialization Process

IMPORTANT NOTE: IF THE POWERTRAIN CONTROL MODULE HAS BEEN CHANGED AND THE CORRECT VIN AND MILEAGE HAVE NOT BEEN PROGRAMMED, A DTC WILL BE SET IN THE AIRBAG MODULE. IN ADDITION, IF THE VEHICLE IS EQUIPPED WITH A SENTRY KEY IMMOBILIZER MODULE (SKIM), SECRET KEY DATA MUST BE UPDATED TO ENABLE STARTING.

The Sentry Key Immobilizer Module (SKIM) Replacement and System Initialization Process can be summarized by the following:
1. Obtain the vehicle's unique PIN number assigned to its original SKIM module from either the vehicle's invoice or from Chrysler's Customer Center.
2. With the DRB, select "Theft Alarm," "SKIM," "Miscellaneous." Select "SKIM Module Replaced" and the DRB will prompt you through the following steps.
3. Program the unique 4 digit PIN number into the SKIM's memory.
4. Program the vehicle's VIN number into the SKIM's memory.
5. Program the county code into the SKIM's memory (U.S.).
6. Transfer the vehicle's unique Secret Key data from the PCM. This process will require the SKIM module to be in secured access mode. The PIN number must be entered into the DRB before the SKIM will enter secured access mode. Once secured access mode is active, the SKIM will remain in that mode for 60 seconds.
7. Program all customer keys into the SKIM's memory. This requires that the SKIM be in secured access mode. The SKIM module will immediately exit secured access mode after each key is programmed. Note: Secured access mode is not required to query the programmed status of the key.

NOTE:
- IF A PCM IS REPLACED, THE UNIQUE SECRET KEY DATA MUST BE TRANSFERRED FROM THE SKIM MODULE TO THE PCM. THIS PROCEDURE REQUIRE THE SKIM TO BE PLACED IN SECURE ACCESS MODE USING THE FOUR DIGIT PIN CODE.
- IF THREE ATTEMPTS ARE MADE TO ENTER SECURED ACCESS MODE USING AN INCORRECT PIN, SECURED ACCESS MODE WILL BE LOCKED OUT FOR ONE HOUR. TO EXIT THIS LOCK OUT MODE, LEAVE THE IGNITION SWITCH IN THE RUN POSITION CONTINUOUSLY FOR ONE HOUR, (ENSURE ALL ACCESSORIES ARE TURNED OFF. ALSO MONITOR THE BATTERY STATE AND CONNECT A BATTERY CHARGER IF NECESSARY).

To program Sentry Keys using the "customer programming" method, which requires two valid Sentry Keys.

Programming Blank Sentry Keys With The DRB
When programming a blank Sentry Key transponder, the key blank must first be cut to match the ignition lock cylinder. It will also be necessary to enter the vehicle's 4-digit PIN code into the DRB to enter the SKIM's secured access mode.

NOTE: ONCE A SENTRY KEY IS PROGRAMMED TO A PARTICULAR VEHICLE IT CANNOT BE TRANSFERRED TO ANOTHER VEHICLE.

Insert the blank key into the ignition and turn it to the Run/Start position. Using the DRB select "Theft: Alarm", then "SKIM", then "Miscellaneous". Select "Program New Key." Enter the 4-digit PIN code using the DRB. When programming is completed, the SKIM will exit secured access mode and display the status of the key. The different status messages are (programming successful, learned key in ignition, maximum key limit exceeded, programming riot attempted or programming failed).

"Programming Successful" is displayed if SKIM Sentry Key programming succeeds.

"Learned Key in Ignition" is displayed if the key in the ignition has already been programmed into that vehicle's SKIM.

"8 Keys Already Learned (At The Maximum) Programming Not Done" is displayed if eight keys have already been programmed into the SKIM. In this case, if a new key needs to be added due to a lost or defective key, the "Erase All Keys" function (requires entering secured access mode) has to be performed. Then the customer's seven keys plus the new key MUST be reprogrammed into the SKIM.

"Programming Key Failed" is displayed if further diagnosis is required.

To learn additional keys, turn the ignition OFF, remove the learned key, and insert the next new blank key. Turn ignition to the Run position and re-enter the secured access mode function and repeat the "Program New Key" procedure outlined above.