Circuit Description
The throttle position sensor is mounted in the accelerator pedal to detect the opening angle of the accelerator pedal. Since this sensor is electronically controlled with hall elements, accurate control and reliability can be obtained. Two sensors are used to detect the accelerator position and a malfunction of the accelerator pedal position sensor. In the accelerator pedal position sensor, the voltage applied to pedal terminals VPA and VPA2 of the ECM changes between 0-5 volts, in proportion to the opening angle of the accelerator pedal. The VPA is a signal to indicate the actual accelerator pedal opening angle which is used for the engine control, and the VPA2 is a signal to indicate the information about the opening angle which is used for detecting a malfunction. 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 DTCs are stored, the throttle valve is locked at a certain opening angle. Also, the whole electronically controlled throttle operation is cancelled until the system returns to normal and the ignition switch is turned OFF. However, the maximum opening angle of the accelerator pedal is limited to 22 degrees when either the VPA or VPA2 circuit is normal. See Fig 1-Fig 4 . Possible causes are:
- Accelerator pedal position sensor.
- VCPA circuit open.
- VPA circuit open or ground short.
- EPA circuit open.
- VPA and VPA2 circuit are shorted.