Tach Pulse Signal
The engine speed signal is generated by an electronic (Hall Effect) ignition. The low voltage ignition primary pulses are monitored at low tension side of ignition coil. Injection timing is regulated by this signal.
The Hall Effect sensor is mounted at crankshaft pully. Sensor energizes ignition amplifier, closing primary circuit and charging ignition coil. Pulse from sensor is amplified and sent to ignition coil where it is used as tachometer (RPM) signal and monitored by the ECU. The ECU transmits signals to the ignition system which opens the primary circuit of the coil and triggers ignition spark.
NOTE:
All voltage tests should be performed with a Digital Volt Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated different in testing procedures.