How to test a Throttle Position Sensor TPS #1203

Throttle position sensors are one of the common causes of surging, stalling and poor engine running. They are susceptible to water ingress which causes corrosion which in turn effects the resistance of the sensor at certain angular positions. This in turn effects the output voltage signal sent to the ECU. As a result the ECU 'thinks' that the actual position of the throttle valve is more or less than it really is (usually more), it then basis its fueling calculations on the 'wrong' throttle position ultimately leading to excessive (or insufficient sometimes) fueling. Knowing the correct way how to testing a TPS is very important, checking throttle closed output voltage, throttle wide open voltage and the progressive change in voltage as the throttle is opened and closed slowly. Any minor 'glitch' in the voltage output, be it a spike (higher) or dip (lower) voltage can indicate a problem with the internal track. If any of these specifications are suspect then the unit must be replaced. This video covers testing a TPS unit with both a digital volt meter (multi-meter) and an oscilloscope. If you have any questions or comments please leave them in the comments section below... Andy Mechanic!