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Home >> Subaru >> 1989 >> RX Automatic >> Repair and Diagnosis >> Engine Performance >> System >> System/Component Tests >> Idle Control System >> By-Pass Air Control Valve (SPFI)
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By-Pass Air Control Valve (SPFI)

  1. With engine running, disconnect electrical connector. Engine speed should drop (a little with engine warm, a lot with engine cold). Reconnect electrical connector. Ensure engine speed returns to previous speed.
  2. If not, turn engine off. Turn ignition switch to "ON" position. Ensure 10-12 volts are available at Black/White wire of air control valve electrical connector.
  3. Turn ignition off. Ensure resistance of Air Control Valve (ACV) is 7.3-13 ohms. If not, replace ACV. Check ACV solenoid for any short to ground. If present, replace ACV.
  4. Attach electrical connector to ACV. Disconnect connector at ECU. Turn ignition on. Ensure 10-12 volts are present at Green/Red wire (terminal No. 45) of ECU. If not, check harness between ACV and ECU.
  5. Turn ignition off and reattach ECU connector. Turn ignition on. Backprobe Green/Red wire (terminal No. 45) of ECU. There should be 1 volt or less for about 1 minute after ignition is turned to "ON" position. After 1 minute, there should be at least 10 volts. If not, check for a bad ground, problem with ECU circuits (sensors) or ECU.
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