P0120

CIRCUIT DESCRIPTION



The throttle position sensor is mounted in the throttle body and detects the throttle valve opening angle. When the throttle valve is fully closed, the IDL contacts in the throttle position sensor are on, so the voltage at the terminal IDL1 of the Engine Control Module (ECM) becomes 0.0 volts. At this time, a voltage of 0.3 - 0.8 volts is applied to terminal VTA1 of the ECM. When the throttle valve is opened, the IDL contacts go off and thus the power source voltage of approximately 12 volts in the ECM is applied to the terminal IDL1 of the ECM. The voltage applied to the terminal VTA1 of the ECM increases in proportion to the opening angle of the throttle valve and becomes 3.2 - 4.9 volts when the throttle valve is fully opened. The ECM judges the vehicle driving conditions from these signals input from terminals VTA1 and IDL1, and uses them as one of the conditions for deciding the air-fuel ratio correction, power increase correction and fuel-cut control etc.

WIRING DIAGRAM

Throttle Position Sensors Circuit:

DTC P0120 - THROTTLE POSITION CIRCUIT MALFUNCTION



HINT:
- DTC P0120 does not indicate if there is open circuit in IDL wiring.
- After confirming DTC P0120 use the OBD II scan tool or LEXUS hand-held tester to confirm the throttle valve opening percentage and closed throttle position switch condition.





INSPECTION PROCEDURE
HINT: If DTCs PO11O, PO115 and PO12O are output simultaneously, E2 (Sensor ground) may be open.






















DTC P0121 - THROTTLE POSITION RANGE/PERFORMANCE PROBLEM





INSPECTION PROCEDURE