Tachometer: Description and Operation

When the ignition switch is in ON (II) or START (III), battery voltage is supplied through fuse 25 to the gauges in the gauge assembly.

Tachometer
The tachometer drive circuit receives pulses from the ignition control module (ICM) in the distributor assembly or the ECM/PCM. The solid-state tachometer then displays these pulses as engine speed. For each 200 pulses per minute from the ignition control module (ICM) or the ECM/PCM, the tachometer displays 100 RPM.