Troubleshooting

DTC P0120 THROTTLE PEDAL POSITION SENSOR/SWITCH "A" CIRCUIT MALFUNCTION

CIRCUIT DESCRIPTION

DTC Detecting Condition:

The throttle position sensor is mounted in the throttle body and detects the throttle valve opening angle.

When the throttle valve is fully closed, a voltage of approximately 0.7 V is applied to terminal VTA of the ECM. The voltage applied to the terminals VTA of the ECM increases in proportion to the opening angle of the throttle valve and becomes approximately 3.5 - 5.0 V when the throttle valve is fully opened. The ECM judges the vehicle driving conditions from these signals input from terminal VTA, uses them as one of the conditions for deciding the air-fuel ratio correction, power increase correction and fuel-cut control, etc.

Wiring Diagram:

Step 1 - 2:

Step 3 - 5:

INSPECTION PROCEDURE

HINT:
- If different DTCs that are related to different Systems are output simultaneously while terminal E2 is used as a ground terminal, terminal E2 may be open.
- Read freed frame data using the hand-held tester or OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, this is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

CHECK FOR INTERMITTENT PROBLEMS

Hand-held tester only:
By putting the vehicle's ECM in the check mode, the 1 trip detection logic is possible instead of the 2 trip detection logic and the sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.

1. Clear the DTCs.
2. Set the check mode.
3. Perform a simulation test.
4. Check the connector and terminal.
5. Handle the connector.