Good morning and thank you for inquiring with JustAnswer, my name is XXXXX XXXXX i will be the teochnician assisting you today. You could have a failed GEM module, a bad 4x4 shift motor on the transfercase or possible loss of vacuum signal to the front hubs. To properly diagnose this concern, the Ford scantool should be used to retrieve any fault codes from the 4x4 module, to allocate the appropriate pinpoint test to follow based on the code. With out the scantool to aid in diagnosis ,you could check the 4x4 shift motor,tap the motor with a hamer a few times to see if this might free up the motor if it is stuck as well as the vacuum hoses going to each hub to mkae sure they are not cracked, brittle or loose. If you can provide me a dtc i can give you the appropriate pinpoint test to test the specific component and its associated wiring. I have posted the symptom chart below for additional information for you to check preliminary
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