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Deceleration Fuel Cut-Off System: Testing

  1. Run engine at idle. Disconnect solenoid valve connector to disable solenoid valve (manifold vacuum will act on air switching valve, causing valve to open). If idle drops excessively or engine stalls, air switching valve and solenoid valve are okay.
  2. If idle speed does not change, check vacuum passage for clogging and check condition of air switching valve or solenoid valve.
  3. With engine idling, battery voltage should be measured at solenoid connector. If voltage is not present, electrical wiring or engine speed sensor is defective.
  4. Increase speed to 1500 RPM. Check to ensure voltage is present at solenoid valve connector. If not, engine speed sensor is defective.
  5. Increase speed to 2500 RPM. Check to be sure no voltage is present at solenoid valve connector. If it is, engine speed sensor is defective.
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