Instrument Panel Cluster (IPC) Description and Operation: Tachometer

The PCM (8.1L) converts the data from the crankshaft position sensor into a 2 pulses/engine revolution signal. The PCM uses the engine speed signal circuit in order to display the engine speed in the IPC. The tachometer defaults to 0 RPM if a malfunction in the engine speed signal circuit exists.

The 6.5L engine uses voltage pulses from the generator via the engine speed signal circuit to determine the engine speed. Solid state circuits convert the pulse frequency in order to move the pointer of the tachometer.