Diagnosis & Repair
NOTE:
Read freeze frame data using hand-held tester or OBD II scan tool, as freeze frame data records engine conditions when malfunction is detected. When trouble shooting, it is useful for determining whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.
For wiring diagram of Corolla model, see Fig 1. For wiring diagram of Matrix model, see Fig 2. For diagnosis and repair with hand-held tester, see Fig 3. For diagnosis and repair with OBD II scan tool, see Fig 4. To check for intermittent problems, see INTERMITTENT PROBLEM CHECK under SELF-DIAGNOSTIC SYSTEM. To identify circuits referenced in testing, See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. To check ECM inputs and outputs, see PIN VOLTAGE CHARTS article. To replace ECM, see REMOVAL & INSTALLATION - 4-CYLINDER article.