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Ecu Power Supply & Ground Tests

  1. Check Main Relay  - Turn ignition off and remove main relay. Connect battery voltage to main relay terminals No. 1 and 2. Ensure there is less than 10 ohms resistance between main relay terminals No. 3 and 5, and between terminals No. 4 and 6. If resistance is less than 10 ohms, go to next step. If resistance is more than 10 ohms, replace main relay.
  2. Check ECU Power Supply Circuit  - Install main relay and disconnect ECU 22-pin connector. Turn ignition on. Ensure there is at least 10 volts between ECU 22-pin connector terminal No. 13 (Yellow/Green wire) and ground, and terminal No. 26 (Yellow/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 ECU Ground Circuit  - Turn ignition off. Ensure there is less than 10 ohms harness resistance between ECU 22-pin connector terminals No. 14 (Black wire) and ground, No. 15 (Black/Yellow wire) and ground, and No. 25 (Black/Brown wire) and ground, and between 26-pin connector terminal No. 11 (Red/Green wire) and ground, and terminal No. 22 (Green/White wire) and ground. If resistance is less than 10 ohms, see IGNITION CONTROL SYSTEM TESTS  . If resistance is more than 10 ohms, repair harness or connectors as necessary.
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