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Ignition Control System Tests

  1. Check Ignition System For Proper Spark  - Remove spark plug wire cap from each spark plug. Install a known-good spark plug to spark plug wire and position spark plug so it is grounded to engine. Crank engine. If a spark does not occur at each spark plug go to next step. If a spark does occur at each spark plug, see FUEL PUMP CIRCUIT TESTS  .
  2. Check Voltage At Ignition Coil Positive Terminal  - Turn ignition off. Disconnect connector from ignition coil. Turn ignition on. Ensure there is at least 10 volts between ignition coil 3-pin harness connector terminal No. 2 and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is as specified, go to next step. If voltage is not as specified, repair harness or connectors as necessary.
  3. Check Ignition Coil  - Measure primary resistance between ignition coil terminals. See IGNITION COIL RESISTANCE  . If resistance is not as specified, replace coil. Measure secondary resistance. See IGNITION COIL RESISTANCE  . If resistances are not as specified, replace ignition coil.
  4. Check Harness Between Ignitor & Ignition Coil Connector  - Turn ignition off. Disconnect connector from ignitor. Measure resistance of harness connector between ignition coil connector terminal No. 5 and ignitor connector terminal No. 1 and ignition coil connector terminal No. 6 and ignitor connector terminal No. 3. Resistance should be one ohm maximum. If resistance is not as specified, repair harness or connector as necessary.
  5. Check Ignitor Input Signal  - Reconnect ignitor connector. Backprobe connector terminals to check voltage between ignitor connector terminal No. 1 and ground, and between ignitor connector terminal No. 2 and ground. Ensure input signal voltage fluctuates with engine speed while cranking. If no voltage, replace ignitor. If voltage is 10 volts or more, go to next step.
  6. Check Harness Of Ignitor Ground Circuit  - Turn ignition off. Disconnect ignitor connector. Measure resistance between ignitor connector terminal No. 3 and engine ground. Resistance should be 5 ohms maximum. If resistance is not as specified, repair harness or connector as necessary.
  7. Check Harness Between ECM & Ignitor Connector  - Disconnect connector from ECM. Measure resistance of harness between ECM and ignitor. See ECM & IGNITOR HARNESS TERMINAL IDENTIFICATION  table. If resistance is more than one ohm, Repair open in harness between ECM and ignitor connector.
    ECM & IGNITOR HARNESS TERMINAL IDENTIFICATION

    ECM Terminal No. Ignitor Terminal No.
    41 1
    40 2
    94 3
  8. Measure resistance of harness connector between ECM connector terminal No. 41 and ground, and between ECM connector terminal No. 40 and ground. Resistance should be one megohm minimum. If resistance is less than specified, repair ground short in harness between ECM and ignitor. If resistance is as specified check for poor contact in ECM connector. If contact is okay, check fuel pump circuit. See FUEL PUMP CIRCUIT TESTS  .
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