US Patent 7411481 Electronic control apparatus for motor vehicle

An ECU of a vehicle is activated to communicate with a user validation apparatus while a specific signal such as an ignition signal is being produced, and to perform a first control operation when positive validation occurs, and can be activated by a request signal for a second control operation while the specific signal is off, without performing the communication. Erroneous detection of a communication error is avoided in a case when communication is interrupted due to switch-off of the specific signal and the request signal for the second control operation is received during that communication.