SMT

DTC P0120 THROTTLE/PEDAL POSITION SENSOR/SWITCH "A" CIRCUIT (SMT)

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The throttle position sensor is mounted on the throttle body, and has 2 built-in sensors to detect the throttle value opening angle and malfunctions of the throttle position sensor.

The voltage applied to 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 VTA is a signal to indicate the actual throttle valve opening angle, which is used for the engine control. The VTA2 is a signal to indicate the information about the opening value 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 VTA and VTA2, and the ECM controls the throttle motor to make the throttle valve angle properly in response to the driving condition.

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

However, the opening angle of the throttle valve can still be controlled by the accelerator pedal through the throttle cable.







HINT: After confirming DTC P0120, use the hand-held tester or the OBD II scan tool to confirm the accelerator pedal opening position percentage. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Condition:

Typical Malfunction Thresholds:

Component Operating Range:

The ECM uses the throttle position sensor to monitor the throttle valve opening angle.

a. There is a specific voltage difference expected between VTA1 and VTA2 for each throttle opening angle.
- If the difference between VTA1 and VTA2 is incorrect, the ECM interprets this as a default and will set a DTC.

b. VTA and VTA2 each have a specific voltage operating range.
- If VTA or VTA2 is out of the normal operating range, the ECM interprets this as a fault and will set a DTC.

c. VTA and VTA2 should never be close to the same voltage levels.
- If VTA is within 0.02V of VTA2, the ECM interprets this as a short circuit in the throttle position sensor system and will set a DTC.

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
- If DTCs related to a different system that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

Step 1 - 2:

Step 3 - 4:

Hand-held tester

Step 1 - 2:

Step 3:

OBD II scan tool (excluding hand-held tester)