Electronic Control Module (ECM)
- ECM in Virgin mode
In this mode, the ECM knows only the model vehicle identifier code.
The engine can be locked/unlocked.
ECM requests to ICU the VIN number. As soon as the ECM receives two correct consecutive communication frames with the same VIN code the ECM learns it.
The VIN code will be stored in non-volatile memory at the end of power latch phase. ECM enters in Learnt mode.
- ECM in Learnt mode
In such a state, ECM checks on every communication, the correct encoding of the ICU.
If the code received is not correct, then the vehicle is immobilized.
The coded 5 bytes of data emitted by ECM are a mixture of MIN code and random.
The coded 5 bytes of data emitted by ICU are a mixture of VIN code and random.
- ECM in Neutral mode
This mode is a special intermediate mode, used for ICU replacement or immobilizer option installation.
ECM request to ICU the VIN number. As soon as the ECM receives two correct consecutive communication frames with the same VIN code the ECM learns it.
The VIN code will be stored in non-volatile memory at the end of power latch phase. ECM enters in Learnt mode.
- After turning on the ignition the ECM will control the engine in a normal way for starting and running while waiting for a valid release response message from the immobilizer.
- After receiving a response message including the information "ICU in learnt mode" and the correct system VIN code.
The ECM enters the release state, which allows to continue the running of the engine.
- After receiving a response message including the information "ICU in learnt mode" and a wrong system VIN code.
The ECM does not send a new request and enters the blocked state, which causes the activation of the immobilization actions of the engine.
- If the ECM does not receive a response message within a defined time from beginning of the release time period or the ECM receives a no release answer.
The ECM enters the blocked state, which causes the activation of the immobilization actions of the engine.
The inactive state of the Immobilizer (valid key/invalid key) ends with turning off the ignition.