Circuit Description

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

Throttle Position (TP) sensor uses 2 sensors which detects throttle opening and a malfunction of the TP sensor. TP sensor is located on throttle body and provides an input voltage of 0-5 volts to VTA and VTA2 terminals at Engine Control Module (ECM) in proportion to throttle opening. ECM uses input signals and controls the throttle control motor to provide proper throttle valve opening in response to driving conditions. DTC is set when improper input signals from TP sensor are received at ECM. If DTC P0121 exists, ECM will turn off the power to throttle control motor and throttle valve is closed by the return spring. When this occurs, throttle valve is controlled by throttle cable connected to accelerator pedal. Possible cause is defective TP sensor.