Testing Procedure for Throttle Position Sensor

[DeKylie]

Throttle position sensor is also known as throttle opening sensor or throttle switch. The testing procedure for throttle position sensor is as follows: 1. Read data stream. When reading the data stream of TPS, slowly press and release the accelerator pedal for observation to prevent floor mats from obstructing the opening or closing of the throttle, which may lead to inaccurate test data. 2. Measure the voltage of throttle position sensor. The signal voltage of throttle position sensor increases with the opening of throttle. When the throttle is fully opened, its signal voltage is close to 5V, and when the throttle is closed (idle), its signal voltage is about 0.5V. 3. Test by unplugging the sensor connector. For cars equipped with automatic transmission, if it is suspected that the abnormal throttle position sensor (TPS) causes the automatic transmission to shift impact, the TPS plug can be unplugged for test driving, and manual shifting can be used. If the upshift and downshift are smooth at this time, it means that the mechanical part of the automatic transmission is normal, the problem lies in the control part, and the TPS may be faulty.

[StEthan]

I usually enjoy tinkering with automotive circuits, and throttle position sensor testing is quite crucial. Before testing, ensure the engine is off and the ignition switch is ON but not started. First, use an OBD scanner to check for trouble codes—common ones like P0120 indicate TPS issues. Next, unplug the sensor connector and inspect the terminals for corrosion or looseness. Take out a multimeter, set it to DC voltage mode, connect the red probe to the signal wire (usually the middle yellow wire), and the black probe to the ground wire (black wire). Then, slowly rotate the throttle shaft—the voltage should smoothly rise from around 0.5V to approximately 4.8V. If it fluctuates or doesn’t change, the sensor is likely internally faulty or worn. Also, check if the reference voltage is around 5V to confirm proper power supply. I often clean oil and grime around the sensor to avoid misdiagnosis. The whole process takes about 20 minutes, and with practice, you can quickly diagnose acceleration lag issues, saving a lot on repair costs. Remember to reset the ECU memory after each test.