Circuit Description
The accelerator pedal position sensor is mounted on the accelerator pedal and has the 2 signal outputs (elements) that are used for engine control and detecting malfunctions in the sensor.
The accelerator pedal position sensor and accelerator pedal are connected by the accelerator wire and the voltage applied to the terminals VPA and VPA2 of the ECM changes between 0 V and 5 V in proportion to the opening angle of the accelerator pedal. VPA signals are used to detect actual accelerator pedal angles, which is useful for engine control. VPA2 signals are used for detecting malfunctions in VPA.
The ECM judges the current opening angle of the accelerator pedal from these signals input from terminals VPA and VPA2 and the ECM controls the throttle motor based on these signals.
If this DTC is stored, the ECM shuts down the power for the throttle motor and the magnetic clutch, and the throttle valve is fully closed by the return spring.
However, the opening angle of the throttle valve can be controlled by the accelerator pedal through the throttle cable.
HINT:
After confirming DTC P1120, use the OBD II scan tool or the hand-held tester to confirm the throttle valve opening angle (voltage).