Tachometer: Description and Operation

The tachometer in the main instrument display panel is supplied with current from fuse 17 via pin 11 (12p-1) of the main instrument display panel. The control pulses needed by the tachometer are obtained from the engine management system via pin 4 (12p-1).

The control pulse is a square wave which varies periodically between Batt+ and 0 V, twice per engine revolution.

Engine rpm Frequency (approx.)
Idling 30 Hz
2500 rpm 83 Hz