Tachometer: Description and Operation

How the Gauges and Indicators Circuit Works

The indicator lights are controlled by different conditions in their associated systems.

Tachometer
The tachometer (part of the LCD display) is controlled by the CPU in the gauge assembly. The CPU receives a pulsing input from the ECM. The frequency and duration of these input pulses are measured by the CPU. The CPU controls the LCD display to turn on the proper segments indicating the engine speed.