DeVille DHS V8-4.6L VIN Y (2000)
Driver/Vehicle Information Display: Description and Operation
Tachometer
The tachometer displays engine RPM (speed), between 0 and 7000 RPM. The engine RPM is calculated by a discrete signal sent to the IPC from the
PCM. The engine speed signal is active low, with a pull-up resistor located in the IPC and connected to switched battery voltage. The signal is a square
wave with a 25 to 75 percent duty cycle. Each engine revolution is represented by two input pulses. Engine speed is calculated using the time difference
between the two consecutive pulses. Accuracy of the final calculations are within 25 RPM.
The tachometer cannot be reset by the driver. The tachometer is displayed as XXXX RPM TACHOMETER. The XXX represents the calculated engine
RPM value. The value will range between 0 and 7000 RPM.