I have a 1997 Control Trac 4.0L OHV with about 130,000 miles on it.
With the selector set on Auto (choices are Auto, 4H and 4L) 4WD is engaged all the time. This is based upon the fact that it's clumping while turning, even on hard dirt (almost new Michelin LTX tires). I did the 'ol clean the transfer case sensors trick and it didn't help. I think the transfer case clutch is engaged all the time but I cannot find a description of the TC clutch either in my Hayne's manual, online, or in my Ford Service Manual on CD. The Ford manual doesn't seem to have this particular problem listed under their diagnostic procedures.
My understanding is that the front differential on the vehicle is a regular "live"open differential and there are no locking hubs. Is this correct? That might explain why one front wheel was spinning while attempting a steep, muddy hill. This kinda stinks if this is the case. Maybe it's time to trade it in on a first generation Explorer.
I removed the servo motor to get to one of the sensors and noticed that the TC choices are H, L, and N. On the 91-94s the choices are 2H, 2L, and 4L. I could not find a position where 4WD was not engaged.
The rear seal on the transfer case is leaking. The fluid looks rather dark. Is it possible that the fluid was contanimated through a minor leak in the seal? Could this be causing the sensors to not work at all? I changed the TC fluid 25,000 miles ago or thereabouts. I suspect that new fluid would probably become dirty soon so is there such a thing as flushing a transfer case? Of course a new seal is imperative.
There is a minor to moderate whine from somewhere around the middle to the front of the vehicle that is constant at a constant speed. It does not change while accelerating/decelerating. There is a slight clunk when coming to a stop, either in D or R. If it had radius arms I'd think it needed new bushings. I've read a lot about replacing ball joints but don't recall the symptoms. Is clunking a sign of bad ball joints, or perhaps bad CV joints? Could worn wheel bearings somehow cause the Contro Trac to go wacky? Or is this whine somehow related to the transfer case problem?
I disconnected the wiring going to the transfer case and 4WD is now disengaged. Is there any problem with driving it with the TC wires disconnected? I've read about the "brown wire" but that wouldn't really fix the problem--it would just make it go away.
I'm going to try to get the codes read but this car is not here most of the time (daughter's car) and unless she crawls underneath and reconnects the TC wiring before getting them read I suspect the code info would be erroneous.