Cartwaveforms > actuators > throttle position > Throttle Potentiometer
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Throttle Potentiometer Waveform Notes
This sensor or potentiometer is able to indicate to the Electronic Control Module (ECM) the exact amount of throttle opening due to its linear output. The majority of modern management systems will employ this particular sensor, and is located on the throttle butterfly spindle. This is a 3 wire device having a 5 volt supply, an earth connection and a variable output from the centre pin. As the output is critical to the vehicle’s performance, any ‘blind spots’ within the internal carbon track’s swept area, will cause ‘flat spots’ and ‘hesitations’. This lack of continuity can be seen on an oscilloscope and will enable the operator to plot the output voltage over its operational range, showing any faulty areas.
A good throttle pot should show a small voltage at the throttle closed position, gradually rising in voltage as the throttle is opened and returning back to its initial voltage as the throttle is shut. Although many throttle position sensor voltages will be manufacturer specific, many are non-adjustable and the voltage will be in the region of 0.5 to 1.0 volts at idle rising to 4.0 volts (or more) with a fully opened throttle. For the full operational range, a time scale around 2 seconds is used.
The picture should be clean with no voltage ‘drop out’ at any particular point, as this small discrepancy will be sufficient to cause a ‘flat spot’ under initial acceleration.
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