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Idle Speed Control (ISC) Valve: 4WD

  1. Warm engine to normal operating temperature. Ensure idle speed is correct. Disconnect ISC valve connector. Engine speed should be above 1000 RPM.
  2. Reconnect ISC valve. Engine should return to idle speed of 700-800 RPM. If engine RPM was not within specification, disconnect ISC valve connector. Using ohmmeter, measure resistance between terminals "B +" and "ISC1" AND "ISC2". See Figure. Replace valve if resistance is not within 16-17 ohms.
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