The purpose of this test is to examine the operation of a Throttle Position Sensor (TPS) potentiometer based on output quality and response time in relation to throttle position.
This known good waveform has the following characteristics:
A throttle position sensor signals the position of the throttle valve to the Engine Control Module (ECM).
Throttle potentiometers are generally carbon track type units mounted directly onto the throttle butterfly spindle. They are a three-wire device with a reference 5 V supply, output signal and earth terminals.
Some manufacturers combine the potentiometer with the throttle actuator motor. Whether combined or separate components, their function remain the same.
As the throttle position is critical to engine control, the normal operating output range of the TPS is within some margin of the earth and reference 5 V supply voltages. For example, from around 0.5 V to around 4.5 V. This provides a means for the ECM to check the integrity of the sensor and circuits: a voltage below or above this expected output range will indicate an open circuit, a short to earth, or a short to the reference 5 V supply. Either of these outcomes will cause the ECM to register a sensor fault.
Faulty Throttle Potentiometer – Symptoms
Faulty Throttle Potentiometer – Causes
Selection of component related Diagnostic Trouble Codes (DTCs):
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