Circuit description

Throttle position sensor is mounted on the throttle body and it have the 2 sensors to detect the throttle opening angle and the malfunction of the throttle position sensor's own.

The voltage applied to the terminals VTA and VTA2 of the ECM changes between 0 V and 5 V in proportion to the opening angle of the throttle valve.

The ECM judges the current opening angle of the throttle valve from these signals input from terminals VTA and VTA2, and the ECM controls the throttle motor to make the throttle valve angle properly in response to driving condition.

If this DTC is stored, the ECM shuts down the power for the throttle motor, and the throttle valve is fully closed by the return spring.

DTC No.

DTC Detecting Condition

Trouble Area

P0120

Condition (a), (b), (c), (d) or (e) continues for 2.0 seconds:

(d) When VTA ^ 0.2 V and ^ 2.0 V, and VTA2 ^ 4.97 V

(e) VTA - VTA2 ^ 0.02 V

• Open or short in throttle position sensor circuit

• Throttle position sensor

• ECM

Condition (a) continues for 0.4 seconds: (a) VTA ^ 0.2 V and VTA2 ^ 0.5 V

HINT:

After confirming DTC P0120, use the OBD II scan tool or TOYOTA hand-held tester to confirm the accelerator pedal opening position percentage.

Accelerator pedal opening position expressed as percentage and voltage

Trouble area

Accelerator pedal released

Accelerator pedal depressed

THROTTLE POS

THROTTLE POS #2

THROTTLE POS

THROTTLE POS #2

0 %

0 V

0 %

0 V

VC circuit open

0 %

2.0 - 2.9 V

0 %

4.6 - 5.1 V

VTA circuit open or ground short

8 - 20 %

0 V

64 - 96 %

0 V

VTA2 circuit open or ground short

100 %

5 V

100 %

5 V

E2 circuit open

_DIAGNOSTICS - ENGINE

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