I just got done replacing the transfer case on my Dad's 2000 Expy because it was stuck in 4Hi. After it was done, I took it on a short drive around town and everything seemed ok, it drove fine and the 4WD finally worked. The problem is as soon as I took it on the highway there was a shudder that felt like the truck was trying to shift into 4WD. I pulled the fuse for the A4WD and took it on the highway again and there was no more shudder. Any ideas? Could one of the sensors for the A4WD be messed up? Is there anyway to test them? Or could the control unit have problems?

 

T-Case shift motor, or one of two wheel speed sensors located in the t-case. I'm probably preaching to the choir here, but make sure the tire sizes are the same all around, and air pressures are within a few pounds of one another.

 

See, now how close do those have to be? The truck needed two of the tires replaced because of a flat, so now the front tires are brand new and the rears have 75% of the tread gone.

 

I had the famous "rumble" when turning from a stop. tried everything. The tires had been on the truck and not properly rotatedm even though there was lots of tread left. When I replaced the tires, the problem went away and has not come back in 20,000 km. When replacing tires on a 4x4 I have been told that it is best to replace all at once. It is all about rotation speed and I would say that if you are looking at 2 old tires with 75 % tread gone and two new tires, you are going to experience some complaints from the system.

 

I'm not sure, but I would guess it is close regarding the new tires and the old ones. Did you replace your speed sensors when you rebuilt the case? Just thought of something; try airing down the newer tires a bit, like tricking the system into thinking all tires are the same, and see if things change. Keep us posted!

 

I am having a similar problem. When the tires spin out in A4WD and then tries to engage 4WD, it then proceeds with a clunking sound that is trying to engage and disengage the 4WD. I just dropped the rig off at Ford and the tech said his first thought is a spring in the transfer case, but I will know more in a few hours.

 

No, we didn't replace the sensors because we just picked up a used case from a 2002 Expy and threw it in. I'll have to try airing down the tires and see what happens. It would be amazing to me if that would fix it because I couldn't believe the system could be that sensitive.

I'm really starting to hate the A4WD on these trucks.

 

I got the rig back and they said that the tires were so off from not being rotated that it was creating the 4WD to engage and disengage and that new tires were the problem. I am putting on new tires today and I will let you know what I find out.

 

I could believe that the 2 new tires are the problem. With these trucks, you need to replace all 4 tires rather than just 2 at a time like some other vehicles.

 

Please.

 

zmock8, first off, what year is your Expy? Over here in the midwest, it's snowing quite a bit and I have to put mine into A4WD to get around. I drive a '98 and I've noticed for quite some time, that when I put mine into A4WD, dry pavement or not, whenever I accelerate at anything more than a leasurely gallop the transfer case seems to "jerk" the car along. Quite annoying after a while but I've never had any problems getting out of 4wd. My brother did have a problem once getting out of 4LO but probably because of his stupidity.

Anyway, do any of you guys have ideas as to what could be wrong? From my experiences, it has no effect on how well the A4WD works, which is pretty solid. Can't beat doing some A4WD donuts though

Thanks again,
-rockstate

 

Well, the tires took care of the problem. Now when it slips in gravel or anything and then right back on to dry pavement, it doesn't continue making the clunking sound going in and out of 4WD. It just goes in and then comes out like it should. I guess the tires were the trick!!!!!!!!

 

Hmmm... Looks like I might have to replace the other two tires so they are all new, even though I really don't want to.