The TPS sensor (Throttle Position Sensor) is located above the throttle body and is a potentiometer. Its function is to detect the angle of the throttle lever. Each time the throttle lever makes a movement, the TPS sends a signal to the Powertrain Control Module (PCM). This sensor has 3 wires which are: One reference of 5 volts, one of ground and the third is a return signal. The third cable is used by the TPS sensor to return information from the throttle position to the Power Train Control Module (PCM).
At the moment when the accelerator is closed, the signal is close to 0.45 volts. When the accelerator is depressed to the bottom (WOT) the signal voltage of the Throttle Position Sensor (TPS) is approximately 5 volts. If the PCM (Power Train Control Module) observes a voltage exceeding the permitted limit, the diagnostic code P0123 OBD2 is established.