Circuit Description

WARNING: This page is about a different car, the 2002 Lexus GS 430. However, it is still accessible from the selected car via links, so may be relevant.

The Throttle Position (TP) sensor is a 2 variable resistor sensor that monitors throttle opening and TP sensor malfunction. Based on TP sensor signal, ECM determines vehicle driving condition and uses throttle control motor to set throttle angle accordingly. If DTC P0120 is set, ECM shuts down power to throttle control motor and electromagnetic clutch.

DTC P0120 is set when ECM consistently detects .2 volt or less, or 4.8 volts or more from VTA circuit, or .5 volt or less from VTA2 circuit for 2 seconds. DTC P0120 is also set when ECM consistently detects .2 volt or more and 2.0 volts or less from VTA circuit, and 4.97 volts or more from VTA2 circuit for 2 seconds.

DTC P0120 is also set when ECM consistently detects .02 volt or less from VTA and VTA2 circuit for 2 seconds. DTC P0120 is also set when ECM consistently detects .2 volt or less from VTA circuit and .5 volt or less from VTA2 circuit for .4 second. Possible causes are:

Open or short in TP sensor circuit.
Faulty TP sensor.
Faulty ECM.