Transfer case tries to shift between gears...while I'm going down the expressway

[downzero]

So I'm headed down I-80 today at 70 mph and my transfer case apparently tried shifting into 4 high (or rather didn't stay in 2 high) while I'm flying down the highway. This resulted in a nasty vibration of the whole truck which would not stop until I stopped the vehicle. It did it 3 times in about 150 miles until finally it'd do it every time within about 30 seconds of leaving the shoulder.

I managed to get home by shifting into 4wd high, leaving the front hubs unlocked, and driving home (60 miles) this way.

My transfer case motor is about two years old. Could it just randomly find itself lost and start shifting while I'm moving without leaving me an error code?

The noise I heard was so awful that I thought the transmission was going to come out from under the truck. Let me tell ya, it ain't fun.

Truck is a 2000 Ranger, XL, 3.0, 5 speed, with a lot of miles on it.

 

[Liberto]

I'm gonna assume your talking about the 2000 ranger in your sig. Also i did some research on this because I thought I was having a similar problem... I think I read that in 2000 they had a separate module for the 4wd systems unlike the previous rangers that had them built into the GEM module behind the radio (if I'm correct) you should find the control module behind the passenger side kick panel and ford quoted me $292 for the module. My advice? Go to a junk yard rip one out throw it in. If it clears your problem up then you know the $290 part is your problem

 

[hoohah797]

Not sure about the 2000, but on the '01 Ranger 4WD control module is on the passenger side floor below the fuel pump reset switch. Plastic panel just pulls off, square black box, cant miss it.