Part 2 of 2
SKIS OPERATIONWhen ignition power is supplied to the SKIM, the SKIM performs an internal self-test. After the self- test is completed, the SKIM energizes the antenna (this activates the transponder chip) and sends a challenge to the transponder chip. The transponder chip 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 transponders.
Challenge - This is a random number that is generated by the SKIM at each ignition key cycle.
The secret key and challenge are the two variables used in the algorithm that produces the encrypted response message. The transponder uses the crypto algorithm to receive, decode and respond to the message sent by 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 at any one time). After validating the key the SKIM sends a PCI 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 again. After twenty 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 message. 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 message 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 Red Warning lamp located in the Instrument Cluster. The lamp is illuminated when the SKIM sends a PCI Bus message to the instrument cluster requesting the lamp on. The SKIM will request lamp operation for the following:
- bulb check at ignition on
- to alert the vehicle operator to a SKIS malfunction
For all faults except transponder faults and VIN mismatch, the lamp remains on steady. In the event of a transponder fault the light flashes at the rate of 1 Hz (once per second). If a fault is present the lamp will remain on or flashing for the complete ignition cycle.
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 integrity 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. relay and solenoids) and short circuits (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, PCM and transponder chip (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 vehicle four-digit PIN.
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. (THE VEHICLE WILL STILL RUN). 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).
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 PROGRAMMED TO THE NEW SKIM.
1. Turn the ignition ON (transmission in Park/Neutral).
2. Use the DRB and select THEFT ALARM, SKIM then MISCELLANEOUS.
3. Select SKIM MODULE REPLACEMENT (GASOLINE).
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).
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 vehicle 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 TRANSFERRED TO ANOTHER VEHICLE.
If ignition key programming is unsuccessful, the DRB will display one of the following messages:
Program Not Attempted
The DRB attempts to read the programmed key status and there are no keys programmed 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 selecting MISCELLANEOUS and ERASE ALL CURRENT IGN. KEYS.
3. Program all ignition keys.
Learned Key In Ignition
Ignition key transponder ID is currently programmed in SKIM memory.
DIAGNOSTIC TROUBLE CODES
Each diagnostic trouble code is diagnosed by following a specific testing procedure. The diagnostic 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 DRB III
Hard Code
A diagnostic trouble code that comes back within one cycle of the ignition key is a hard code. This means that the defect is there every time the powertrain control module checks that circuit or function. Procedures verify if the trouble code is a hard code at a the beginning of each test. When it is not a hard code, an intermittent test must be performed.
Codes that are for OBDII monitors will not set with just the ignition key on. Comparing these to nonemission codes, they will seem like an intermittent. These codes require a set of parameters to be performed (The DRB III pre-test screens will help with this for MONITOR codes), this is called a TRIP. All OBDII DTCs will be set after one or in some cases two trip failures, and the MIL will be turned on. These codes require three successful (no failures) TRIPS to extinguish the MIL, followed by 40 warm-up cycles to erase the code. For further explanation of TRIPS, Pre-test screens, Warm-up cycles, and the use of a the DRB III, refer to the On Board Diagnostic training booklet # 81-699-97094.
Intermittent Code
A diagnostic trouble code that is not there every time the PCM checks the circuit is an intermittent code. Most intermittent codes are caused by wiring or connector problems. Defects that come and go like this are the most difficult to diagnose; they must be looked for under specific conditions that cause them. The following checks may assist you in identifying a possible intermittent problem:
- Visually inspect related wire harness connectors Look for broken, bent, pushed out, or corroded terminals.
- Visually inspect the related harnesses. Look for chafed, pierced, or partially broken wire.
- Refer to any Hotline Newsletters or technical service bulletins that may apply.
- Use the DRB III data recorder or co-pilot.
- Use the DRB III PEP module lab scope.
Reset Counter
The reset counter counts the number of times the vehicle has been started since codes were last set, erased, or the battery was disconnected. The reset counter will count up to 255 start counts.
The number of starts helps determine when the trouble code actually happened. This is recorded by the PCM and can be viewed on the DRB III as STARTS since set.
When there are no trouble codes stored in memory, the DRB III will display NO DTC'S Detected and the reset counter will show STARTS since clear = xxx.
Handling No Trouble Code Problems
Symptom checks cannot be used properly unless the driveability problem characteristic actually happens while the vehicle is being tested.
Select the symptom that most accurately describes the vehicle's driveability problem and then perform the test routine that pertains to this symptom. Perform each routine test in sequence until the problem is found. For definitions see Glossary of Terms.
SYMPTOM DIAGNOSTIC TEST
Hard Start Checking Secondary Ignition System
Checking Engine Vacuum
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Checking Engine Mechanical Systems
Checking EVAP Emission System
Checking EGR System (if equipped)
Checking IAT Sensor
Start And Stall Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Hesitation/Sag/Stumble Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking Engine Vacuum
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Checking Engine Mechanical Systems
Checking EVAP Emission System
Checking EGR System (if equipped)
Checking IAT Sensor
Checking PNP Switch
Surge Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Checking Evap Emission System
Lack Of Power/Sluggish Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking the minimum idle air flow
Checking idle air control motor operation
Checking EGR system (if equipped)
Spark Knock/Detonation Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Checking EVAP Emission System
Cuts Out/Misses Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking The Fuel Delivery
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Checking EGR System (if equipped)
Backfire/Popback Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking The Fuel Delivery
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking for Oxygen Sensor Switching
Checking EGR System (if equipped)
Runs Rough,
Unstable/Erratic Idle Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking Engine Vacuum
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Checking Engine Mechanical Systems
Checking EVAP Emission System
Checking EGR System (if equipped)
Checking IAT Sensor
Checking PNP Switch
Poor Fuel Economy Checking Secondary Ignition System
Checking PCM Power And Ground Circuit
Checking Engine Vacuum
Checking The Fuel Delivery
Checking Coolant Sensor Calibration
Checking TPS Calibration
Checking MAP Sensor Calibration
Checking The Minimum Idle Air Flow
Checking Idle Air Control Motor Operation
Checking Engine Mechanical Systems
Checking EVAP Emission System
Checking EGR System (if equipped)
Checking IAT Sensor
Checking PNP Switch