Tachometer: Description and Operation

When the ignition is in ON (II) or START (III), battery voltage is supplied through fuse 5 to the gauges in the gauge assembly.

With the ignition in ON (II) or START (III), the tachometer drive circuit in the gauge assembly receives pulses from the Engine Control Module (ECM). The ECM determines the engine speed from the crankshaft position/cylinder position (CKP/CYP) sensor. The number of pulses per minute is directly proportional to the engine speed. The tachometer drive circuit controls the tachometer.