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.

Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected. If COOLANT TEMP displayed in freeze frame data is less than 176°F (80°C), there is a possibility that misfire only exists during warm-up.

For diagnosis and repair procedure, see Fig 2-Fig 8 . When instructed to "Perform Confirmation Driving Pattern", go to TEST DRIVE CONFIRMATION procedure.

NOTE: When step 8) of Diagnosis & Repair procedure is reached, inspection of injector waveform patterns is recommended. If oscilloscope is available, fuel injector operation on misfiring cylinder may be checked by reading the fuel injector signal waveform pattern and fuel injector duration signal waveform pattern which may be checked by connecting oscilloscope between ECM 31-pin connector E8 terminal No. 21 (White/Black wire) and fuel injector driver terminal at ECM with engine idling. For fuel injector driver identification, see Fig 1 and IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS . Fuel injector signal waveform pattern and fuel injector duration signal waveform pattern should be properly displayed within proper intervals. See Fig 9.

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 vacuum or EVAP hose routing, see VACUUM DIAGRAMS article. For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article or SYSTEM & COMPONENT TESTING - 4-CYLINDER article. For adjustments, see ON-VEHICLE ADJUSTMENTS - 4-CYLINDER article. For information on checking valve timing, see appropriate article in ENGINES. Repair engine as necessary. For removal and installation of components, see REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.

Fig 1: ECM/Fuel Injectors Wiring Diagram (Tacoma 4-Cylinder)