Throttle Position Sensor (TPS)

The TPS is mounted on side of throttle body, opposite throttle lever. It measures throttle valve rotational 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 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 (throttle closed) or less. An ALDL "Scan" tester may be used to check TPS voltage.