I have a '97, 5-speed with the "auto/4HI/4LO switch. The 4WD engages itself during turns on dry surfaces (roads, parking lots, anywhere). At the minimum it causes the truck to jerk back and forth as you turn. In one instance, it snapped the drive shaft within the transmission right in the middle of oncoming traffic in an intersection, stopping the vehicle and necessitating replacement of the tranny, transfer case and clutch. Within months it was doing it again and I had Ford run a diagnostic. They want me to replace the whole drive system again because their computer says there is nothing wrong with the Explorer's computer therefore it must be in the mechanical parts. However a mechanic I trust tells me that he believes either the Explorer's computer or the 4WD wheel sensors are faulty and telling the 4WD drive motor to engage. Every other Ford service department (6 total) I have spoken with has a different answer. All of them swear they've never seen this problem before.
Does anyone have an idea or a possible solution short of replacing the drive chain?