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Home >> Hyundai >> 2000 >> Accent GL, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0300: Random Misfire Detected >> Test Procedures
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Test Procedures

  1. Turn ignition on. Connect scan tool to data link connector and verify DTC P0300 is set. If DTC P0300 is the only DTC set and fuel is at least 87 octane, go to next step. If other DTCs are set, repair other DTCs first. If fuel octane is less than 87, refuel with 87 or higher octane fuel and retest, clear DTC and verify operation.
  2. Turn ignition off. Disconnect ignition coil connector. Turn ignition on. Measure voltage between ground and ignition coil connector terminal No. 1 (Light Green wire on coil No. 1; Orange wire on coil No. 2). If battery voltage is present, go to next step. If battery voltage is not present, repair open in wire between ignition switch 6-pin connector terminal No. 4 (Orange wire) and ignition coil. When repairs are completed, clear DTC and verify operation.
  3. Turn ignition off. Disconnect ECM 81-pin connector. Using jumper wires connect ignition coil connector terminals No. 2 (Blue wire on coil No. 1; Brown wire on coil No. 2) to ground. Measure resistance between ground and ECM harness connector terminal No. 2 for coil No. 1 and terminal No. 5 for coil No. 2. If resistance is one ohm or less, remove jumper wires and go to next step. If resistance is more than one ohm, repair open in suspect circuit between ignition coil and ECM. When repairs are completed, clear DTC and verify operation.
  4. Reconnect ECM 81-pin harness connector. Turn ignition switch to START position. Measure voltage between ground and ignition coil connector terminal No. 1 (Light Green wire on coil No. 1; Orange wire on coil No. 2). If voltage varies between 0.02-0.2 volt on both circuits, go to next step. If voltage does not vary between 0.02-0.2 volt on either circuit, ensure ECM harness connector terminals are clean and tight. If connector is okay, replace ECM. When repairs are completed, clear DTC and verify operation.
  5. Turn ignition off. Disconnect ignition coil connector and spark plug wires from coil. Measure primary coil resistance between ignition coil terminals No. 1 and 2 of both coils. If primary coil resistance is 0.45-0.55 ohm, go to next step. If primary coil resistance is not 0.45-0.55 ohm, replace ignition coil. When repairs are completed, clear DTC and verify operation.
  6. Measure resistance of secondary coils between ignition coil spark plug connector terminals No. 1 and 4, and between terminals No. 2 and 3. If secondary coil resistance is 10,300-13,900 ohms, go to next step. If secondary coil resistance is not 10,300-13,900 ohms, replace ignition coil. When repairs are completed, clear DTC and verify operation.
  7. Inspect the following components/systems and ensure they are operating properly:
    • Spark plugs and spark plug wires.
    • Clogged, leaking or damaged fuel injectors and wiring.
    • Obstructed airflow meter.
    • Acceleration sensor wiring harness.
    • Canister purge valve for normal operation.
    • Vacuum hoses and connections.

    If all components/systems are operating properly, go to next step. Repair or replace components/systems as necessary. When repairs are completed, clear DTC and verify operation.

  8. Perform fuel pressure inspection. See FUEL PRESSURE TEST under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not as specified, repair fuel system as necessary. If fuel pressure is within specification and no pressure leak-down is detected, check engine oil for proper level and for contamination (fuel or water in oil). If engine oil is okay, ensure ECM connector terminals are clean and tight. If ECM connector is okay, replace ECM. When repairs are completed, clear DTCs and verify operation.
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