Circuit Description

WARNING: This page is about a different car, the 1995 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.

The TPS is variable resistor that monitors throttle opening. The ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. Code is set when ECM consistently detects less than .1 volt from VTA circuit and closed throttle position switch is off. Code can also be set if ECM consistently detects 4.9 volts or more. Code P0120 will not set if there is an open in IDL circuit. Possible causes are:

TPS sensor open or short circuit.
TPS sensor malfunction.
ECM malfunction.

NOTE: If Codes P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit. Repair as needed. See wiring diagram in the WIRING DIAGRAMS article.