Tachometer: Description and Operation

How the Circuit Works
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.. The solid-state tachometer then displays these pulses as engine speed. For each 200 pulses per minute from the Ignition Control Module (ICM), the tachometer displays 100 RPM.