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Ignition Control System Tests: Legacy

  1. Check Ignition System For Proper Spark  - Remove injector sub-harness and plug wire cap from each spark plug. Install a known good spark plug to plug wire and position spark plug so it is grounded to engine. Verify each spark plug has a spark as engine is turned over. If a spark does not occur at each spark plug, connect injector sub-harness and plug wires and go to next step. If a spark does occur at each spark plug, see LEGACY under FUEL PUMP CIRCUIT TESTS  .
  2. Check Voltage At Ignition Coil Positive Terminal  - Turn ignition on. Verify at least 10 volts between ignition coil 3-pin connector terminal No. 2 (Yellow/Red wire) and ground. 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  - Remove ignition coil connector and remove ignition coil. Measure resistance of ignition coil primary and secondary windings. If resistance is as specified, go to next step. If resistance is not as specified, replace coil. On primary side, verify .7 ohm resistance between 3-pin connector terminal No. 2 (Yellow/Red wire) and plug wire coil tower No. 1 or 3 (closest to 3-pin connector). On secondary side Hitachi coil, verify 13,800 ohms resistance between plug wire coil towers No. 1 and 2, and No. 3 and 4. On secondary side Diamond coil, verify 21,000 ohms between plug wire coil towers No. 1 and 2, and No. 3 and 4. See Figure .
  4. Check Ignitor Output Signal  - Connect all connectors. Measure voltage between ignitor output connector terminal No. 1 (Yellow/Blue wire) and ground, and terminal No. 2 (Green/White wire) and ground while cranking engine. If at least .1 volt is present, go to next step. If at least .1 volt is not present, replace ignitor.
  5. Check Harness Between ECU & Ignitor  - Turn ignition off and disconnect ECU and ignitor connectors. Verify zero ohms between ECU connector terminal No. 9 (Green/White wire) and ignitor terminal No. 2, ECU connector terminal No. 10 (Yellow/Blue wire) and ignitor terminal No. 1, ECU connector terminal No. 15 (Black wire) and ignitor terminal No. 3 (Black wire) and ground. Verify no continuity between ignitor terminal No. 1 (Yellow/Blue wire) and ground, and between ignitor terminal No. 2 (Green/White wire) and ground. If resistance is as specified, inspect ECU connector and repair as necessary. If ECU connector is okay, replace ECU. If resistance is not as specified, repair harness or connectors as necessary.
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