Case A

If the first key detected at the Ignition ON transition is locked and well programmed (authentication by encryption), the ISU memorizes the serial number of this key (used as identifier), and validates this key (increasing the number of learnt keys). Then and, up to 3 more keys can be learnt by successive Ignition ON transitions whatever the key status (locked or virgin). The Learning mode ends:

• By validation with a Diagnosis request key learning end. The keys are definitively saved, the flag keys learning successful is set, and the ISU switches to nominal mode operation (learnt mode); It is now ready to emit the VIN-code to EMS control unit at the next Ignition ON transition.
• By cancellation with Diagnosis, request cancel key learning, or time-out expiring, or power supply cut-off. The ISU returns then in its previous configuration (virgin mode).