ABSTRACT
The issues and diagnostic techniques used for sensors and actuators are common to many systems. Testing sensors to diagnose faults is usually a matter of measuring their output signal. In some cases, the sensor will produce this on its own (e.g. an inductive sensor). In other cases, it will be necessary to supply the correct voltage to the device to make it work. Most vehicle sensors produce an electrical signal, so checking their output on an oscilloscope is often the recommended method. ‘Actuators’ is a general term used here to describe a control mechanism. When controlled electrically, they will work either by a thermal or by a magnetic effect. An example of a thermal actuator is the movement of a traditional type fuel or temperature gauge needle. A further example is an auxiliary air device used on many earlier fuel injection systems.
