Abstract: A device for testing the mass airflow sensor for a motor vehicle provides for connecting the positive and negative terminals of dc source to the corresponding positive and negative terminals on the mass airflow sensor. A circuit comprised of an LED and a resistor connected in series has one end connected to the positive terminal of the dc source and another end connected to the signal output terminal of the MAF sensor during a test. If, after the tester is connected to the dc source and to the MAF sensor the LED does not flash at all or burns continuously, it is a first indication of a defective MAF sensor. Because the flash or pulse rate of the signals driving the LED are too fast for visual counting, a tachometer or frequency meter is connected between the LED circuit and the negative terminal of the dc source. The meter needle deflects on a scale calibrated in terms of frequency or engine rpm which quantities are both related to mass airflow.

Abstract: A tester is adapted to plug in or otherwise connect to an ignition control module under test. The tester includes an LED in series with a resistor. The series circuit is connected between a battery and a contact in the connector which provides the control module with an electric load in substitution for the ignition coil primary associated with the vehicle engine. If, after the tester is connected to the ignition control module and to a battery, the LED is turned on bright, it is one indication of a failed switching transistor in the module. The tester is provided with a flexible lead terminating in a contact which is touched to a predetermined terminal of the ignition control module. If the LED flashes on and off in correspondence with the terminal being touched, it is an indication of the control module being capable of processing ignition timing signals and of the switching transistor in the module being good.

Abstract: An apparatus for testing the operativeness of a Hall effect device (HED), such as in an automotive application, without requiring removal of the HED for testing. The apparatus includes a connector for connection to the HED, a connector for connection to a voltage supply, and an indicator. A permanent magnet is physically positioned with respect to the HED so that a properly functioning HED would produce a Hall effect current within a predetermined range. A ferrous metal strip is provided, shiftable between an interference position between the permanent magnet and the HED and a clear position not between the permanent magnet and the HED. The indicator is connected so as to be lit when the HED is producing a current within the predetermined range, and not lit when the HED is not producing a current within the predetermined range. Also disclosed is a method for testing the operativeness of a HED. The method includes supplying a testing apparatus as described above.