TEST1: Testing The Throttle Position Sensor Voltage Signal. The successfully diagnose the TPS as good or bad, we need to know that: The TPS produces a voltage signal. This voltage signal increases as the throttle plate opens. At wide-open-throttle (WOT), the TPS produces about 4.5 Volts DC. Im not sure how many people will bother to figure out the entire code. If I've have guessed correctly and your code is P0123, the signal from the TPS is higher than anticipated. The ECM feeds the TPS (and the MAP / air temp sensor) 5 volts. You should probably find the 5v supply wire and check the voltage. Doingthis can help keep your exhaust system clean in addition to your air intake system. Bad Throttle Body Vs. Faulty Throttle Position Sensor. Most modern cars utilize a throttle position sensor (TPS) to determine the position of the throttle. In contrast, older vehicles use a mechanical linkage that connects the gas pedal to the throttle body. Hereis how to diagnose a bad throttle position sensor TPS on a car or truck. The throttle position sensor in this video is on a Chevrolet pick up truck. Mos Reply 1 - 11 of 11 Posts. fourwd1 · #2 · Jan 10, 2010. A faulty TPS can cause driveability problems such as hesitation, stalling, an erratic idle, pinging (spark knock), no torque converter lockup, hard starting, an intermittent check engine light while driving, poor fuel economy, and generally poor engine performance. 2Mw2U1.

how do you know when your tps sensor is bad