Operation CHARM: Car repair manuals for everyone.

Tachometer

The Tachometer displays Engine speed in rpm. Voltage pulses are taken from the Powertrain Control Module and applied to the Tachometer via CKT 121. The Tachometer responds to the frequency of the voltage pulses which increases with Engine speed. Solid state circuits process these pulses into a signal that drives the pointer of the Tachometer.