PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
Back-pinning Probe Set
Flexible Back-pinning Probe
PicoScope Battery Clip
*At Pico we are always looking to improve our products. The tools used in this guided test may have been superseded and the products above are our latest versions used to diagnose the fault documented in this case study.
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):
This help topic is subject to changes without notification. The information within is carefully checked and considered to be correct. This information is an example of our investigations and findings and is not a definitive procedure. Pico Technology accepts no responsibility for inaccuracies. Each vehicle may be different and require unique test settings.
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