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Home >> Subaru >> 2003 >> Outback Base, 4D Wagon, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.5L >> Diagnostic Tests >> DTC P1446: Fuel Tank Sensor Control Valve Circuit, Low Input >> Diagnostic Procedure
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Diagnostic Procedure

  1. Turn ignition switch to on position. Measure voltage between ground and ECM 35-pin harness connector, terminal No. 1 by backprobing ECM harness connector. See Figure. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, go to step  3.
  2. Check for poor contact in ECM harness connector. If poor contact is found, repair as necessary. If contact is okay, the system has returned to normal at this time.
  3. Turn ignition switch to off position. Disconnect ECM and fuel tank sensor control valve harness connectors. Measure resistance between ground and fuel tank sensor control valve 2-pin harness connector, terminal No. 2. See Figure. If resistance is greater than one megohm, go to next step. If resistance is less than one megohm, repair short to ground and test system operation. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  4. Ensure ignition switch is in the off position. Measure resistance between ECM 35-pin harness connector, terminal No. 1 and fuel tank sensor control valve 2-pin harness connector, terminal No. 2. See Figure and Figure . If resistance is less than one ohm, go to next step. If resistance is greater than one ohm, repair open circuit between ECM and fuel tank sensor control valve harness connectors. See WIRING DIAGRAMS under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  5. Ensure ignition switch is in the off position. Measure resistance between fuel tank sensor control valve 2-pin harness connector terminals No. 1 and No. 2. See Figure. If resistance is 10-100 ohms, go to next step. If resistance is not 10-100 ohms, replace fuel tank sensor control valve.
  6. Turn ignition switch to on position. Measure voltage between ground and fuel tank sensor control valve 2-pin harness connector, terminal No. 1. If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair open circuit between main relay and fuel tank sensor control valve. See WIRING DIAGRAMS under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  7. Check for poor contact in fuel tank sensor control valve. If poor contact is found, repair as necessary. If contact is okay, contact authorized Subaru dealership because probable cause is deterioration of multiple parts.
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