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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 P0447: EVAP System Vent Control Circuit, Low Input >> Diagnostic Procedure
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Diagnostic Procedure

  1. Perform basic diagnostic procedure. See BASIC DIAGNOSTIC PROCEDURE . Turn ignition on. Using voltmeter connected to ground, backprobe ECM 35-pin connector B134 (Baja, Legacy and Outback) or B137 (Forester and Impreza), terminal No. 3. See Figure. If voltage is more than 10 volts, go to next step. If voltage is not more than 10 volts, go to step  3.
  2. Check for poor connection at ECM connector. If connection is okay, circuit has returned to normal. If connection is poor, repair as necessary.
  3. Turn ignition off. Disconnect drain valve connector and ECM 35-pin connector. Using an ohmmeter connected to ground, measure resistance at drain valve connector terminal No. 2. See Figure. If resistance is not less than 1 megohm, go to next step. If resistance is less than 1 megohms, locate and repair short to ground in wiring between ECM and drain valve connectors. See ENGINE PERFORMANCE in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  4. Using an ohmmeter, measure resistance between drain valve connector terminal No. 2 and ECM 35-pin connector, terminal No. 3. If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, locate and repair open circuit in wiring and check for poor terminal contact in connectors between ECM and drain valve.
  5. Turn ignition off. Disconnect harness connector from drain valve. Using an ohmmeter, measure resistance across drain valve terminals. If resistance is between 10 and 100 ohms, go to next step. If resistance is not between 10 and 100 ohms, replace drain valve.
  6. Turn ignition on. Using DVOM connected to ground, measure voltage at drain valve terminal No. 1. If voltage is more than 10 volts, go to next step. If voltage is not more than 10 volts, locate and repair open circuit in wiring and check for poor terminal contact in connectors between main relay and drain valve.
  7. Check for poor contact at drain valve connector. Repair connector as required. If connection is okay, contact authorized Subaru dealership because probable cause is deterioration of multiple parts. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
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