Patent ID: 8258795

Claim:
A method for checking an operational capability of an electric circuit that has at least one sensor module and a diagnostic mechanism, the sensor module comprising an integrated switching circuit, at least one output terminal connected to the diagnostic mechanism and power supply terminals to which an operating voltage is applied via cables, the method comprising: switching said sensor module to a test mode, in which the sensor module emits a predefined communication test signal from the at least one output terminal, the test signal differing from a constant signal level; reading said test signal by the diagnostic mechanism; comparing the test signal with a predefined tolerance band range in order to verify that the communication with the sensor module is operational; testing the operation of the integrated switching current if said communication with the sensor module is verified as operational; transmitting an error signal from said sensor module via the output terminal to the diagnostic mechanism, if the switching circuit is not operational; transmitting a function signal from the sensor module via the output terminal to the diagnostic mechanism if the switching circuit is operational, wherein the functional signal is different from the error signal and the functional signal is dependent on a voltage residing at the power supply terminals; and comparing the function signal received by the diagnostic mechanism with a predefined tolerance range, wherein the presence or absence of an error in the cable is confirmed based on the result of this comparison.