Circuit Description

The throttle position sensor is mounted on the throttle body and it has 2 sensors to detect the throttle opening angle and a malfunction of the throttle position sensor.

The voltage applied to the terminals VTA1 and VTA2 of the ECM changes between 0 V to 5 V in proportion to the opening angle of the throttle valve. The VTA1 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 throttle valve from these signals input from terminals VRA1 and VTA2, and the ECM controls the throttle motor to make the throttle valve angle properly in response to the driving condition.

When a malfunction is detected, 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.

Fig 1: Throttle Pedal Position Sensor/Switch Circuit Diagram (High Input)

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Fig 2: DTC Detection Condition Table

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HINT:

Fig 3: DTC P0122 & P0123 Chart

NOTE: When a malfunction is detected, 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.

HINT:

After confirming DTCs, use the hand-held tester or the OBD II scan tool to confirm the throttle valve opening percentage and closed throttle position switch condition.
The THROTTLE POS means VTA1 signal as well as the "THROTTLE POS #2" for the VTA2 signal.
Reference (Normal condition):

Fig 4: Accelerator Pedal Released & Depressed Chart
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