Circuit Description

WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.

The accelerator pedal position sensor is a 2 variable resistor sensor that monitors throttle opening and accelerator pedal position sensor malfunction. ECM controls throttle motor and electromagnetic clutch based on signal from accelerator pedal position sensor. If DTC P1120 is set, ECM shuts down power to throttle control motor.

DTC P1120 is set when ECM consistently detects .2 volt or less, or 4.8 volts or more from VPA1 circuit, or .5 volt or less from VPA2 circuit for 2 seconds. DTC P1120 is also set when ECM consistently detects .2 volt or more and 1.8 volts or less from VPA1 circuit, and 4.97 volts or more from VPA2 circuit for 2 seconds.

DTC P1120 is also set when ECM consistently detects .2 volt or less from VPA1 or VPA2 circuit for 2 seconds. Possible causes are:

Open or short circuit in accelerator pedal position sensor.
Faulty accelerator pedal position sensor.
Faulty ECM.