Key Replacement

This is the procedure used in After Market to replace the keys, or to learn additional keys. If an ISU control unit in learnt mode receives the Diagnosis request key learning start which allows to get the Access code corresponding to the vehicle and registered at the Factory.

• If the key detected at the Ignition On transition is locked, the ISU tries to authenticate it.

If it is 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). If not, the key is refused: the learning of this key is not successful. The ISU waits for a new Ignition ON transition.

• If the key detected at the Ignition ON transition is virgin (non locked), the ISU learns this key (by programming, authenticating and eventually locking it).

The Learning mode ends:

• By validation with a Diagnosis request key learning end. The keys are definitively saved, and the flag keys learning successful is set, and the ISU switches to nominal mod 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.