Circuit Description

WARNING: This page is about a different car, the 2003 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

The accelerator pedal position sensor is mounted on the accelerator pedal bracket and it has 2 sensors to detect the accelerator position and a malfunction of the accelerator position sensor. Voltage applied to pedal terminals VPA and VPA2 of ECM changes between 0-5 volts in proportion to opening angle of the accelerator pedal. VPA is a signal to indicate the actual accelerator pedal opening angle which is used for the engine control, and VPA2 is a signal to indicate the information about the opening angle which is used for detecting a malfunction. ECM judges the current opening angle of the accelerator pedal from these signals input from terminals VPA and VPA2. ECM controls throttle motor based on these signals. If DTCs are stored, throttle valve is locked at a certain opening angle. Electronically controlled throttle operation is cancelled until the system returns to normal and the ignition switch is turned OFF. See Fig 1 and Fig 2 . Possible causes are:

Open or short in accelerator pedal position sensor circuit.
Faulty accelerator pedal position sensor.
Faulty ECM.

Fig 1: Identifying Accelerator Pedal Position Sensor Operation

Fig 2: Identifying Accelerator Pedal Position Sensor Circuit