Description:
Programmed by the OEM, this parameter is used by the ECM to convert the engine speed signal into revolutions per minute for a tachometer.
Available:
All electronically controlled on-highway engines covered in this handbook
Range:
Advantages:
By using the ECM Output to drive the in-dash tachometer the need for a separate sensor for the tachometer is eliminated.
Recommendations:
For most applications the factory default is correct.
For ECM driven tachometer applications the indash tachometer must be set to the same pulses per revolution (PPR) setting as the ECM.
To verify that the ECM is driving the tachometer, perform the tachometer special test in Cat ET. When running the special test, the tachometer reading should sweep to approximately 1500 rpm. If not, use the following calculation to correct the Tachometer Calibration parameter value.
PPR = current Tachometer Calibration value
Tach = value displayed on the tachometer during the test
X = the desired Tachometer Calibration value
1500 = value that should be displayed on the tachometer during the test