Theory Of Operation

NORMAL OPERATION: 

• Wireless Ignition Node (WIN) or Wireless Control Module (WCM):  On vehicles equipped with a WCM/WIN, the Secret Key data is a component of the encryption data used by the WCM/WIN for programming Keys/FOBIKs. Each WCM/WIN comes from the manufacture pre-programmed with its own unique Secret Key. When the vehicle is built this Secret Key data is used to program the Key/FOBIK and a back-up copy of the Secret Key data is stored in the PCM. The WCM/WIN unique secret key data then becomes the Original Secret Key for that vehicle. When a new Key/FOBIK is added and programmed, the secret key data in the WCM/WIN is used for the programming. The Key/FOBIK programming procedure permanently changes the Key/FOBIK so after it is programmed it becomes dedicated to that WCM/WIN.
  NOTE:

  No new Keys/FOBIKs can be programmed to the vehicle if the P0633 DTC is active. Follow the repair procedure below to correct the P0633 DTC active condition before attempting to program new Keys/FOBIKs. 

• Powertrain Control Module (PCM):  The PCM stores the backup copy of the Secret Key in case of a WCM/WIN replacement. The original Secret Key data can be transferred from the PCM stored location to the new WCM/WIN. When a PCM is replaced,  the new PCM comes with default Secret Key stored  in the Secret Key location. Running the "PCM Replaced" routine will transfer the original Secret Key and VIN from the WCM/WIN to the PCM. If the VIN is manually written without the "PCM Replaced" routine being performed  the PCM Secret Key data will remain default, but the vehicle will start and run. The PCM checks this location during every ignition on key cycle. If the data stored in this location of the PCM has a default  value, the P0633 DTC sets. This DTC will not illuminate the MIL. It will also not cause any issues with the existing Keys/FOBIKs as long as the default data is not transferred to the WCM/WIN. 

VEHICLE PIN FUNCTION:  Each vehicle has a unique 4 digit PIN number. The PIN is required to enter the Security Access Mode of the WCM/WIN using the scan tool. The WCM/WIN must be placed in the Security Access Mode to permit any programming functions or WCM/WIN configuration changes to occur. The WCM/WIN learns the PIN during its initial programming. Only one PIN can be learned. After the WCM/WIN has learned the PIN it cannot learn another.