The ETCS (Electronic Throttle Control System) is responsible for controlling when the throttle valve opens. This system includes an actuator, the throttle valve, throttle position sensors A and B, the throttle actuator control module, a control module relay, the Accelerator Pedal Position Sensor (APP), and the Engine Control Module (ECM).
The APP sensor is driven by a throttle cable, and in this way, the throttle opening value is calculated after the pedal is pushed. The pedal opening value is transformed into an electrical signal that the APP sensor transmits to the ECM to calculate the goal position. The targeted signal is sent to the Throttle Actuator Control Module, which is responsible for determining the valve position.
The Throttle Actuator Control Module matches the target throttle valve opening angle with the actual opening angle provided by Throttle Position Sensor A. If the comparison shows a large difference exceeding the allowable values, the ECM will receive this information indicating a malfunction and will set a DTC indicating the situation. In the case of OBD2 code P1683, it indicates that the malfunctions were detected by the throttle valve default position spring.