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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 97 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0300, P0301, P0302, P0303, P0304, P0305 & P0306 >> Diagnosis & Repair (Using Hand-Held Tester)

Diagnosis & Repair (Using Hand-Held Tester)

WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. If using OBD-II scan tool, go to step  15. If using hand-held tester, check if any DTCs besides P0300, P0301, P0302, P0303, P0304, P0305 or P0306 are output. If so, diagnose other DTCs first. If no other DTCs are present, go to next step.
  2. Check the connection conditions of wire harness and connectors. Check for disconnection or a breakage in vacuum hose. Repair as necessary. If components are okay, check PCV hose connection. Repair as necessary. If PCV hose connection is okay, go to next step.
  3. Connect hand-held tester to the DLC3. Turn the ignition switch ON and push the hand-held tester main switch ON. Start the engine. Read the number of misfire on the hand-held tester. If a misfire is detected in 1-2 cylinders, go to next step. If a misfire is detected in more than 3 cylinders, go to step  10.
  4. Disconnect the ignition coil with igniter. Remove the spark plug. Check the spark plug type. Check the electrode gap. Ensure recommended spark plug is installed and electrode gap is 0.039-0.051" (1.0-1.3 mm). Disconnect the ignition coil with igniter connector, and disconnect the ignition coil with igniter. Remove the spark plug. Install the spark plug to the ignition coil with igniter, and connect the ignition coil with igniter connector. Disconnect the injector connector. Ground the spark plug. Check if spark occurs while the engine is being cranked. To prevent excess fuel from being injected from the injectors during this test, do not crank the engine for more than 5-10 seconds at a time. If spark jumps across electrode gap, go to step  6. If spark does not jump across electrode, go to next step.
  5. Disconnect the spark plug. Change the normal spark plug. Install the spark plug to the ignition coil with igniter. Disconnect the injector connector. Ground the spark plug. Check if spark occurs while the engine is being cranked. To prevent excess fuel from being injected from the injectors during this test, do not crank the engine for more than 5-10 seconds at a time. If spark jumps across electrode gap, replace spark plug. If spark does not jump across electrode gap, check for open or short in harness and connector between ignition coil with igniter and ECM. Repair as necessary. If no open circuit is found, replace ignition coil with igniter, then confirm that there is no misfire.
  6. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM connector and measure voltage between ground and fuel injector terminals at specified ECM connector. See Fig 1. See IDENTIFYING FUEL INJECTOR TERMINALS  table. See Figure. With the engine idling, measure waveform between terminals No. 10-60 and E01 of ECM. See Fig 2. If voltage is 9-14 volts at each terminal, go to step  8. If voltage is not 9-14 volts at each terminal, go to next step.
    Fig 1: Checking Voltage At ECM Connector
    G00165056Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 2: Checking Injector Signal Waveform
    G00165057Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    IDENTIFYING FUEL INJECTOR TERMINALS

    Fuel Injector No. Terminal No. Wire Color
    1 (1) 5 White
    2 (1) 6 Yellow
    3 (2) 1 Black
    4 (2) 2 Blue
    5 (2) 3 Red
    6 (2) 4 Green
    (1) Terminal is located in ECM harness connector E8. See Figure.
    (2) Terminal is located in ECM harness connector E9. See Figure.
  7. Check resistance of injector of misfiring cylinder. Resistance should be 13.4-14.2 ohms at 68°F (20°C). Replace injector as necessary. If injector is okay, check for open and short in harness and connector between ignition switch and injector, injector and ECM of misfiring cylinder. Repair or replace harness or connector as necessary. If harness and connector are okay, go to next step.
  8. Check injector injection of misfiring cylinder. Replace injector as necessary. If injector is okay, check compression pressure of misfiring cylinder. Repair as necessary. If compression pressure is okay, check valve clearance of misfiring cylinder and adjust as necessary. If valve clearance is okay, go to next step.
  9. If misfire is in 1-2 cylinders, go to next step. If misfire is in more than 3 cylinders, check for intermittent problems.
  10. Check valve timing. Check for loose and jumping teeth of timing belt. Adjust valve timing as necessary. If valve timing is necessary, go to next step.
  11. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. Replace fuel pump, pressure regulator, fuel pipe line or filter as necessary. If components are okay, go to next step.
  12. Check mass air flow meter. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Replace as necessary. If mass air flow meter is okay, go to next step.
  13. Check engine coolant temperature sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Replace as necessary. If engine coolant temperature sensor is okay, go to next step.
  14. If misfire is in 1-2 cylinders, problem is intermittent. If misfire is in more than 3 cylinders, go to step  4.
  15. Using OBD-II scan tool, check if any DTCs besides P0300, P0301, P0302, P0303, P0304, P0305 or P0306 are output. If so, diagnose other DTCs first. If no other DTCs are present, go to next step.
  16. Check the connection conditions of wire harness and connectors. Check for disconnection or a breakage in vacuum hose. Repair as necessary. If components are okay, check PCV hose connection. Repair as necessary. If PCV hose connection is okay, go to next step.
  17. Disconnect the ignition coil with igniter. Remove the spark plug. Check the spark plug type. Check the electrode gap. Ensure recommended spark plug is installed and electrode gap is 0.039-0.051" (1.0-1.3 mm). Disconnect the ignition coil with igniter connector, and disconnect the ignition coil with igniter. Remove the spark plug. Install the spark plug to the ignition coil with igniter, and connect the ignition coil with igniter connector. Disconnect the injector connector. Ground the spark plug. Check if spark occurs while the engine is being cranked. To prevent excess fuel from being injected from the injectors during this test, do not crank the engine for more than 5-10 seconds at a time. If spark jumps across electrode gap, go to step  19. If spark does not jump across electrode, go to next step.
  18. Disconnect the spark plug. Change the normal spark plug. Install the spark plug to the ignition coil with igniter. Disconnect the injector connector. Ground the spark plug. Check if spark occurs while the engine is being cranked. To prevent excess fuel from being injected from the injectors during this test, do not crank the engine for more than 5-10 seconds at a time. If spark jumps across electrode gap, replace spark plug. If spark does not jump across electrode gap, check for open or short in harness and connector between ignition coil with igniter and ECM. Repair as necessary. If no open circuit is found, replace ignition coil with igniter, then confirm that there is no misfire.
  19. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM connector and measure voltage between ground and fuel injector terminals at specified ECM connector. See Fig 1. See IDENTIFYING FUEL INJECTOR TERMINALS  table. See Figure. With the engine idling, measure waveform between terminals No. 10-60 and E01 of ECM. See Fig 2. If voltage is 9-14 volts at each terminal, go to step  22. If voltage is not 9-14 volts at each terminal, go to next step.
  20. Check resistance of injector of misfiring cylinder. Resistance should be 13.4-14.2 ohms at 68°F (20°C). Replace injector as necessary. If injector is okay, check for open and short in harness and connector between ignition switch and injector, injector and ECM of misfiring cylinder. Repair or replace harness or connector as necessary. If harness and connector are okay, go to next step.
  21. Check for open or short in harness and connector between ignition switch and injector. See ENGINE PERFORMANCE in WIRING DIAGRAMS article in ELECTRICAL.
  22. Check injector injection of misfiring cylinder. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article.
  23. Check valve clearance of misfiring cylinder. Adjust valve clearance as necessary. If valve clearance is okay, go to next step.
  24. Check valve timing. Check for loose and jumping teeth of timing belt. Adjust valve timing as necessary. If valve timing is necessary, go to next step.
  25. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. Replace fuel pump, pressure regulator, fuel pipe line or filter as necessary. If components are okay, go to next step.
  26. Check mass air flow meter. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Replace as necessary. If mass air flow meter is okay, go to next step.
  27. Check engine coolant temperature sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Replace as necessary. If engine coolant temperature sensor is okay, problem is intermittent.
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