The Electronic Throttle Control (ETC) system consists of the throttle body, Throttle Position Sensor (TPS) 1 & 2 and Accelerator Position Sensor (APS) 1 & 2. TPS 1 & 2 share the same source voltage and ground. The PCM controls the throttle motor to open and close the throttle valve. The TPS1 output voltage increases in proportion with the throttle valve opening after starting. TPS2 output voltage decreases in proportion with the throttle valve opening angle after starting. The TPS provides feedback to the PCM to control the throttle motor in response to the APS.