LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2000 >> RAV4 Base, FWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Engine Control System Self-Diagnostics) >> Diagnostic Tests >> DTC P0300: Random Misfire Detected >> Diagnosis & Repair
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnosis & Repair

WARNING: This page is about a different car, the 2000 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check vacuum hoses for leaks, blockage and proper routing. See appropriate illustration in VACUUM DIAGRAMS article. Also, check wiring and connectors for damage or poor connections. If problem exists, repair as necessary and perform TEST DRIVE CONFIRMATION . If problem does not exist, go to next step.
  2. Check spark and ignition system. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Access ECM below stereo, behind instrument panel, just in front of center console. Turn ignition on. Using DVOM, backprobe ECM connector and measure voltage between ground and fuel injector terminals at appropriate ECM harness connector. See IDENTIFYING FUEL INJECTOR TERMINALS  table. See Figure or Figure . If voltage is 9-14 volts at each terminal, go to step  6. If voltage is not 9-14 volts at each terminal, go to next step.
    IDENTIFYING FUEL INJECTOR TERMINALS

    Fuel Injector No. Terminal No. Wire Color
    With 4A/T Transmission (1)
    1 1 Yellow
    2 2 Black/Red
    3 3 White
    4 4 Black
    Without 4A/T Transmission (2)
    1 12 Yellow
    2 11 Black/Red
    3 25 White
    4 24 Black
    (1) Terminals are located at ECM harness connector E7. See Figure.
    (2) Terminals are located at ECM harness connector E4. See Figure.
  4. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace fuel injector.
  5. Check for open or short in wiring between ECM and fuel injector. See WIRING DIAGRAMS article. If problem exists, repair as necessary. If problem does not exist, repair open or short in injector power source circuit. See WIRING DIAGRAMS article.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check Manifold Absolute Pressure (MAP) sensor and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace appropriate component. If problem does not exist, go to next step.
  9. Check engine compression. See BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. If engine compression is okay, check valve clearance. See ON-VEHICLE ADJUSTMENTS - 4-CYLINDER article. If valve clearance is okay, it may be necessary to check valve timing. See appropriate article in ENGINES.
scientia non olet · About LEMON Manuals