Troubleshooting the Isuzu Shift on the Fly Mechanism

Two things to check:

• The First is the vacuum switching valves on the shift on the fly actuator. Check for corrosion in the connector or in the end of the vacuum lines as seen in the picture below. If there is no corrosion found check the resistance of both vacuum switching valves. The normal resistance is 42 ohms.
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• On other models with a shift motor on the front axle check the shift motor for rust or corrosion inside the shift motor by removing the cover as seen below:

  
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