Abstract: An active tester for vehicle circuit evaluation includes a signal source for generating a dynamic signal, such as an AC current, for injecting to a circuit under test. The tester includes a data storage device for storing at least one test parameter and a data processor for processing data. In operation, the data processor controls to apply the dynamic signal to the separated points of the circuit via the first set of terminals. The response of the circuit under test to the applied dynamic signal is measured. The data processor determines a dynamic parameter of the circuit under test as a function of the dynamic signal and the response. The data process then generates a test result related to the characteristics of the circuit as a function of the at least one test parameter and the determined dynamic parameter. The test result is compared with specification values to determine whether the circuit under test works normally.

Abstract: The present invention related generally to a method for determining spark plug malfunction and more particularly to a method for determining spark plug malfunction in an internal combustion engine in which at least two spark plugs are disposed in each cylinder. In a dual plug configuration, a spark plug malfunction is detected by disabling one of the spark plugs during a test period in a particular cylinder. A misfire provides an indication of malfunction of the other spark plug.

Abstract: A process for recognizing ignition failures in an internal-combustion engine which has two spark plugs per cylinder, based on a measurement of the ionic current at the spark plugs. In this process, the ionic current signals of the two spark plugs are each integrated using an assigned integrator over an entire combustion cycle and the integrator values are compared with one another. Since, in the case of a defective spark plug, an ionic current signal will occur only some time after the ignition (specifically after the arrival of the flame from the ignited spark plug), its integration value is significantly lower than that of the intact spark plug. From this information, the correct operation of the spark plugs is determined.