| Diagnosis and Testing Refer to Wiring Diagrams Section 419-01B, for schematic and connector information. Principles of Operation The ignition key on vehicles with a PATS system is identified by a blue insert. Previous ignition keys with a red insert are not compatible with this vehicle and must not be used. Each ignition key must be programmed into the central junction box (CJB) using the WDS before it can be used to start the engine. NOTE:If a there is concern within the PATS, when the ignition key is turned to the RUN or START position, the PATS light emitting diode (LED) may stay ON for one minute. If this condition occurs, less than the minimum number of ignition keys are stored in the CJB. This will cause the engine to start a total of six times only. NOTE:If a non-programmed ignition key is used to attempt to start the engine, the ignition key must be left in the RUN or START position for a minimum of twenty seconds before any attempt is made to start the engine with the correct programmed ignition key. The only method available to program a new ignition key to the PATS system, is by using the WDS to program the ignition key into the PATS.
REFER to: Key and Remote Transmitter Programming Using Diagnostic Equipment (419-01B Anti-Theft - Passive, General Procedures).
The PATS transceiver communicates with the transponder in the ignition key. The PATS transceiver is located around the ignition lock cylinder and contains an antenna connected to a small module. During each vehicle start sequence, the PATS transceiver reads the ignition key identification code and sends the data to the CJB. The CJB carries out all of the PATS control functions, such as receiving the identification code from the ignition key and controlling engine enable. The CJB initiates the encoded ignition key interrogation sequence when the vehicle ignition switch is turned to RUN or START. When the ignition key is turned to the OFF position, the CJB will remain powered up for approximately 0.16 milliseconds. This allows time for the CJB to store the rolling code in its memory. The PATS uses a visual PATS LED which is situated within the instrument cluster. The PATS LED will self-test for three seconds when the ignition switch is turned to RUN or START under normal operation. The PATS also flashes the PATS LED every two seconds at ignition OFF to act as a visual deterrent. The PATS LED also acts as a diagnostic lamp which will flash different codes depending on the PATS concern present. When the ignition key is turned to the RUN or START position and a PATS concern is present, the PATS LED will flash for one minute before flashing out the relevant fault code(s). It will flash the code(s) a total of ten times before resetting. Code Flashing Example: Code 21. - 0 = LED OFF
- 1 = LED ON
- A = Two Flashes
- B = One Flash
- C= Three second delay period
- D = Repetition of flash code (10 times)
When the PATS LED begins to flash the code(s), it will indicate the first digit of the code by flashing in one second intervals until the number of flashes is equal to the first digit of the code. The PATS LED will then stop flashing for approximately two seconds before the second digit of the code(s) is displayed in the same way as the first. The PATS LED will then stop flashing for approximately three seconds before the process is repeated up to a total of ten times. Inspection and Verification - Verify the customer concern.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Ignition lock cylinder
- PATS ignition key
- Non-PATS ignition key
- Unprogrammed ignition key
- More than one PATS key on key chain
| - Fuse(s)
- Wiring harness
- Electrical connector(s)
- PATS transceiver
- CJB
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the cause is not visually evident, verify the symptom and refer to the Symptom Chart.
Symptom Chart | Symptom | Possible Sources | Action | | Engine does not turn over and the PATS LED is flashing code 11. | * PATS transceiver not connected. | * CHECK the PATS transceiver electrical connector for correct installation. | | Engine does not turn over and the PATS LED is flashing code 12. | * PATS transceiver. | * INSTALL a new PATS transceiver.
REFER to: Passive Anti-Theft System (PATS) Transceiver (419-01B Anti-Theft - Passive, Removal and Installation).
| | Engine does not turn over and the PATS LED is flashing code 13. | * No ignition key data was received. * The CJB has failed to correctly store an ignition key code. | * Non-PATS ignition key used. INSTALL a new ignition key.
REFER to: Key and Remote Transmitter Programming Using Diagnostic Equipment (419-01B Anti-Theft - Passive, General Procedures).
| | Engine does not turn over and the PATS LED is flashing code 14. | * Only part of the ignition key data was received. | * CHECK the PATS transceiver electrical connector for correct installation. * CHECK the battery voltage. * CHECK the ignition key. * REFER to the WDS. | | Engine does not turn over and the PATS LED is flashing code 15. | * The ignition key being used does not match one of those stored in the CJB. | * PROGRAM the ignition key.
REFER to: Key and Remote Transmitter Programming Using Diagnostic Equipment (419-01B Anti-Theft - Passive, General Procedures).
If a non-matching ignition key was used, TURN the ignition ON for a minimum of 20 seconds before starting the engine with a correct ignition key. REFER to the WDS. | | Engine does not turn over and the PATS LED is flashing code 21. | * Less than the minimum number of ignition keys required for normal system operation is stored in the CJB. | * PROGRAM more ignition keys.
REFER to: Key and Remote Transmitter Programming Using Diagnostic Equipment (419-01B Anti-Theft - Passive, General Procedures).
| | Engine does not turn over and the PATS LED is flashing code 23. | * Ignition key status has not been sent to the CJB. | * REFER to the WDS. | | The PATS LED is always or never on - does not go out after three seconds when the ignition key is in the RUN or START position. | * Circuit. * PATS LED. * CJB. | * REFER to the WDS. | | 
