Engine Speed Sensor: Description and Operation

The hall effect sensor signal is also used to determine the engine speed. The sensor generates a square wave signal which the ECU "reads". The frequency of this pulse indicates the speed of the engine. The ECU counts the number of pulses per unit of time and calculates the rpm of the engine. This information is compared to information from other sensors to determine engine load and establish points on ignition and fuel enrichment "maps" which are permanently stored in the ECU's memory. For more information on the hall effect sensor, see HALL SENSOR.