Okay, so a sign that the electronics are good. I'll submit that you hear it try to shift in and out of 4WD but maybe it never gets out when it thinks it does.

This would be similar in feel to a 4WD locked in 4WD, the rear tires are trying to go as fast as the front as the front tires are trying to go as slow as the rear, with those little gears and shafts stuck in the middle making it happen. A wheel binding and unbinding might actually trigger a traction-control event doing this, but I bet overall you're feeling front and rear of the driveline binding.

I bet when the road is wet this behavior seems easier to overcome?

Removing the antilock fuse would stop the ABS system from intervening when it would otherwise do so. I do not know if it stops wheel speed from being monitored for the purpose of traction control.

Were those vehicles AWD vehicles?

Cool! This is how many of us here learn new stuff.

I'd hold off on this. It sounds from your comments above like the logic is working fine. Better test: Get all four wheels in the air while AWD is selected. Can the front driveshaft be turned easily? If not, the center differential is not unlocking as it should.

Owner'* manual won't help a lot here. Perhaps you meant service manual?

ok, I will try to get all fours up and see what I can find.

So I changed rear diff fluid and added the additive. It seems to have helped a little but still having the same issues. I got all fours off of the ground but unfortunately I was in the air so I didn't get a good look at what was going on under the truck. I will have to get it up again to check the front axle. The fella that put me in the air said there was a little play in the rear axles but he didn't think it was enough to cause my issues. Can I unhook the transfer case and manually shift to AWD to see if that is the issue? Think I seen a video somewhere but I would like a second opinion as that vehicle wasn't an AWD.

I had the fella check my uv joint while I was in the air and he said it looked good to him.

Ok, so I got the truck up in my garage today. Here'* what I found: Front axle doesn't turn freely. When in awd all four tires are engaged but when I hit the brakes the front left tire shakes pretty violently and the peddle goes all the way to the floor and it is very hard to gain control, this does not happen when the truck is on all fours, at least it isn't noticeable. When in 4 lo the front left tire and the rear right tires are the only ones turning, the brakes engaged normally this way. So I think that I may not be fully disengaging 4wd and probably have issues with the antilock brakes. Where do I go from here? Can I unhook the actuator on the transfer case and manually shift the case back to regular awd? Opinions appreciated.

Thanks for your help. I still haven't figured out the problem but as it has developed a new problem with the engine I have decided to sell the truck as a whole or part it out. I need to be on the road every day and can't afford to be in the garage every week. Thanks again for your help and ideas.