Tachometer: Description and Operation

Circuit Description
When the ignition switch is in the ON or START position, battery voltage is applied to the gauges (speedometer, tachometer, fuel gauge and engine coolant temperature gauge) from fuse 28.

Tachometer
The tachometer displays engine speed in rpm. Voltage pulses are taken from the ignition system and sent to the tachometer. The tachometer responds to the frequency of the voltage pulses, which vary according to engine speed. The PCM process these pulses into a signal that causes the gauge needle to move.