LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2004 >> Matrix Base, FWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 38 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P1120: Accelerator Pedal Position Sensor Circuit Malfunction >> Diagnosis & Repair (Using OBD-II Scan Tool)
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair (Using OBD-II Scan Tool)

WARNING: This page is about a different car, the 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Access ECM under protective cover, behind left headlight in engine compartment. Turn ignition on. Backprobing, measure voltage between terminals No. 35 (Blue/Yellow wire) and No. 34 (Brown wire) at ECM E4 connector. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  2. Turn ignition on. Backprobing, measure voltage between terminals No. 34 (Brown wire) and No. 33 (Pink/Blue wire) at ECM E4 connector. With fully closed throttle, voltage should be .3-.9 volt. With Wide Open Throttle (WOT), voltage should be 3.2-4.8 volts. Measure voltage between terminals No. 34 (Brown wire) and No. 32 (Blue/White wire) at ECM E4 connector. With fully closed throttle, voltage should be 1.8-2.7 volts. With WOT, voltage should be 4.7-5.1 volts. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  3. Check accelerator pedal position sensor operation. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - GS300, IS300, GS430 & LS430 article. Replace accelerator pedal position sensor as necessary. If accelerator pedal position sensor is okay, check for short or open circuit in wiring harness and sensor connector between ECM E4 connector and accelerator pedal position sensor. See WIRING DIAGRAMS article. Repair wiring as necessary.
scientia non olet · About LEMON Manuals