How to connect an external tachometer

The principle of operation of Electromechanical and electronic tachometers is that they read the number of pulses supplied to the ignition coil (petrol engines) or from terminal W alternator (diesel engines). The number of pulses coming from the output of the generator (at the same engine speed), about 6 times higher than the number of pulses supplied to the ignition coil. Therefore, acquiring the tachometer, be sure to ask the seller whether this device to work properly on your car. There are universal tachometers, in which a special switch that allows you to connect the device to different engines (diesel – petrol, 2, 4, 5, 6, 8 cylinders).

To connect the tachometer in the car with the ignition system, install and secure it to a convenient place on or near the dashboard. Negative terminal (black) connect to ground (the body) of the car. Plus power (red) connect to the terminal of the ignition switch where you receive 12 Volts when you turn on the ignition system. The third wire (tachometer input) connect to the terminal of the ignition coil, which is connected to the breaker points of the distributor (contact ignition system) or to switch (contactless ignition system). On many models of external tachometers provides illumination of the device in the dark. Connect the tach backlight to switch the dimensions of the car.

In a vehicle with a diesel engine, connect the input wire of the tachometer to terminal "W" of the generator. If such terminals have no your generator, take her well-insulated wire. To do this, remove and disassemble the alternator. Moving away from the winding three wires to the built-in generator rectifier. Connect to any of the three wires and neatly print the wire out. Assemble the generator, ensure the cable does not touch moving parts.