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7.3L Diesel

  1. Connect tachometer. Place transmission in Neutral or Park. Start engine and bring to normal operating temperature. Disconnect fast idle solenoid from harness and apply battery voltage to activate solenoid.
  2. Rev engine momentarily to set solenoid. Fast idle should be 800-850 RPM. Adjust by turning solenoid plunger. See Figure. Recheck fast idle and adjust if necessary. Reconnect solenoid connector.


  1. Place transmission in Neutral or Park and bring engine up to normal operating temperature. Check idle speed with transmission in Neutral (M/T) or Drive (A/T). Ensure curb idle adjustment screw is against the stop. If adjustment screw is not against the stop, correct linkage.
  2. Connect tachometer and check curb idle speed. Idle speed should be 600-700 RPM. Adjust idle speed using curb idle speed adjustment screw. See Figure. Repeat check, and adjust again if necessary.
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