Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Toyota Tacoma. However, it is still accessible from the selected car via links, so may be relevant.

After confirming DTC P0120, use Toyota hand-held tester or scan tool to confirm throttle valve opening percentage with throttle fully closed and fully open to determine probable cause. If percentage displayed is always zero percent, VC circuit may be open or VTA circuit may be open or shorted. If percentage displayed is always approximately 100 percent, E2 circuit may be open. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

NOTE: While performing this procedure, below are all related links to specifications and instructions.

For diagnosis and repair procedure, see Fig 1, Fig 2 & Fig 3 .

For wiring diagrams, see appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. When access to, or replacement of ECM is necessary, Engine Control Module (ECM) is located behind glove box. See Figure. For ECM connector terminal view, see Figure. For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article or SYSTEM & COMPONENT TESTING - 4-CYLINDER article. For removal and installation of components, see REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.

Fig 1: DTC P0120 Diagnostic Procedure (Step 1)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: DTC P0120 Diagnostic Procedure (Steps 2-3)

Fig 3: DTC P0120 Diagnostic Procedure (Step 4)