Throttle Position Sensor (TPS)

The TPS, mounted on throttle body, opposite to throttle lever, measures throttle valve movement and transmits a voltage signal to ECM. A variable resistor (potentiometer) within the TPS changes its resistance (voltage drop) in relation to throttle position. A Scan tester is used to measure TPS voltage.

A 5-volt reference voltage is supplied to the TPS, and a signal circuit transmits dropped voltage to ECM. With ignition on and engine off, TPS voltage signal should be 1.25 volts or less (throttle closed) to about 4.5 volts at Wide Open Throttle (WOT).