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Cold Engine

  1. Disconnect and plug lower air suction hose from anti-afterburn valve. Remove air cleaner cover and filter. Start engine and check for bubbling noise at air suction port at idle. If a bubbling noise is not heard, proceed to step 5).
  2. If bubbling noise is heard, check for voltage at air suction control solenoid valve (Yellow/Green wire). If there is voltage, check for voltage at control unit connector (Blue wire) with ignition on. There should be voltage.
  3. If no voltage, check Blue wire between ignition coil and control unit. Check 15 MPH speed sensor, thermosensor, intake air temperature sensor, vacuum switch A and vacuum switch C. Check for voltage at control unit connector (Black/Yellow wire) with ignition on.
  4. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. There should be continuity.
  5. If bubbling noise is not heard, disconnect vacuum hose No. 5 from air suction cut-off diaphragm. If there is vacuum, replace air suction control solenoid valve and retest. If no vacuum, replace air suction cut-off diaphragm and retest.
  6. Ensure engine coolant is below 95°F (35°C) for Calif. models or 122°F (50°C) for Federal models. Disconnect intake air temperature switch connector. Check for a bubbling noise at idle. If noise is heard, see HOT ENGINE  test.
  7. If bubbling noise is not heard, check for voltage at air suction control solenoid valve (Yellow/Green wire). If there is no voltage, check for voltage at control unit connector (Blue wire) with ignition on. There should be voltage.
  8. If no voltage, check Blue wire between ignition coil and control unit. Check 15 MPH speed sensor, thermosensor, intake air temperature sensor, vacuum switch A and vacuum switch C. Check for voltage at control unit connector (Black/Yellow wire) with ignition on.
  9. There should be voltage. If no voltage, check wiring. Check Brown/Black wire for continuity between control unit and ground. There should be continuity. If there is voltage, replace air suction control valve and retest.
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