FX4 4 wheel drive kicking in and out

[jeremytharp]

I've got an 05 4.0 FX4 in the shop. Friend of mine and I put in used motor with low miles, trans, and transfer case. Its kicking in and out of 4 wheel drive with a hard shift every few seconds. I didn't know before we changed everything that he was having this problem before we threw the new transfer case in. I also had a rebuilt transfer case motor put in.
don't know if it could just be in the switch itself or what?
Any help would be great

 

[RonD]

More likely the control module
Google: Ford TCCM 2C54-7H473

The shift motor has contacts where it attaches to the transfer case, these tell the control module the position of the shift motor's gear that turns the transfer case shaft.
There is usually a sensor on the transfer case as well to confirm its gear position.
Picture here: http://www.therangerstation.com/tech_library/TCaseshiftmotor.htm

If one of these wires for the shift motor or sensor is shorting to another wire or a ground the control module might think position has change and it is correcting it by moving the shift motor.
Or it could be module is bad.

It could be a button but that would be less likely, unless they didn't work at all

 

[gw33gp]

What is happening that tells you it is kicking in and out of 4WD? Is the light gong on and off or are you getting a jolt from the drive train under acceleration? Does it do it when just cruising in a straight line?