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Ignition Control System Tests: IMPREZA

  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 IMPREZA under FUEL PUMP CIRCUIT TESTS  .
  2. Check Ignition Coil Power Supply Circuit  - Turn ignition off and disconnect Gray 3-pin ignition coil connector. Turn ignition on. Verify at least 10 volts between ignition coil connector terminal No. 2 (Blue/Red wire) and ground. If at least 10 volts are present, go to next step. If at least 10 volts are not present, repair harness or connectors as necessary.
  3. Check Ignition Coil  - Verify .7 ohm resistance between ignition coil connector terminals No. 1 and 2, and No. 2 and 3. Verify 13,800 ohms resistance between spark plug wire towers opposite each other. If specified resistance is present, go to next step. If specified resistance is not present, replace ignition coil. See Figure .
  4. Check Harness Connector Between Ignition Coil & Ignitor  - Turn ignition off and disconnect Gray 6-pin ignitor connector. Measure harness resistance between ignition coil connector terminal No. 1 (Blue/Red wire) and ignitor connector terminal No. 5 (Blue wire), and between coil connector terminal No. 3 (Red/Green wire) and ignitor connector terminal No. 6 (Red/Green wire). If resistance is less than 10 ohms, go to next step. If resistance is more than 10 ohms, repair or replace harness connector as necessary.
  5. Check Input Signal For Ignitor  - Turn ignition off and connect ignition coil and ignitor connectors. Measure voltage between ignitor 6-pin connector terminal No. 1 (Yellow/Blue wire) and ground, and between terminal No. 2 (Green/White wire) and ground. Crank engine and verify voltage fluctuates between .1-3.4 volts. If voltage fluctuates, go to next step. If voltage does not fluctuate, replace ignitor.
  6. Check Ignitor Harness Connector Ground Circuit  - Turn ignition off. Verify less than 10 ohms resistance between ignitor connector terminal No. 3 (Black wire) and ground. If resistance is as specified, go to next step. If resistance is not as specified, repair harness or connectors as necessary.
  7. Check Harness Connector Between ECU & Ignitor  - Turn ignition off. Disconnect ECU 26-pin and 22-pin Green connectors. Verify less than 10 ohms resistance between ECU connectors and ignitor connector. Measure between 22-pin connector terminal No. 20 (Green/White wire) and ignitor connector terminal No. 2 (Green/White wire), and between terminal No. 21 (Yellow/Blue wire) and terminal No. 1 (Yellow/Blue wire). On ECU 26-pin connector, measure between terminal No. 14 (Black wire) and ignitor 6-pin connector terminal No. 3 (Black wire). Verify one megohm resistance between 22-pin connector terminal No. 20 (Green/White wire) and ground, terminal No. 21 (Yellow/Blue wire) and ground, and 26-pin connector terminal No. 14 (Black wire) and ground. If harness resistance is not as specified, repair harness or connectors as necessary. If harness resistance is as specified, inspect and repair ECU connectors. If ECU connectors are okay, replace ECU.
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