We thought our front axle was going out and took our 99 Expedition to our mechanic. He informed us our 4WD was stuck. He doesn't work on it, but referred us to someone else who can get us in on Monday. In the meantime, my husband found a site online where someone else had the same problem only they couldn't remember exactly how they fixed it. Big help. I was hoping maybe someone on here could give us an idea and maybe save us some money. We would appreciate any help. Thanks!

 

Sometimes if you disconnect the battery for 10 minutes then reconnect it, the problem will be gone. (Sometimes!)

 

Thanks! It didn't fix the problem, but it did do something to where when I change it to 4WD you can hear it change now. Before, it didn't even do that. Maybe that's a sign that it isn't completely broken at least. It gives me hope.

 

Your profile says 99 so I assume that is what you have. On this year there are two ways to put the truck in 4wd. If the drive train computer senses a speed difference between the front and rear drive shafts it will engage an electric clutch to lock the truck in 4wd. The other way is through the switch on the dash which moves a shift motor to either 4wd hi or 4wd low. Most likely since this came out of the blue the problem is on the electric clutch side unless you were using 4wd? As mentioned this is engaged by a speed difference between the front and rear drive shafts. This can come from mismatched tire sizes etc... These trucks are overly sensitive to tire size differences as the truck thinks either the front or rear is going faster. One easy way to test this is pull the 4wd clutch fuse, it is in the box by the brake reservoir and then drive it. Careful though as you can break a half shaft if you are on pavement and in 4wd as the drive line will "bind up". Pretty sure you already know what that feels like. OK now the bad news if for some reason the electric clutch is not being told to engage "pink wire on transfer case all by itself" and shift motor is indeed not in 4wd "three bolts to remove shift motor and look" then most likely the 4wd clutch itself is hung up by a .50 cent plastic collar that likes to split and gets wedged in the engage position. That .50 cent part will require the transfer case to be removed and split and repaired and sadly with today's labor it won't be pretty. I did mine in my garage and it took about 2 1/2 days.

Dave

 

Thanks for the ideas. I'll have my husband check in the morning. As far as the 50 cent part, luckily we have a really fair mechanic (he didn't charge a cent to check it and tell us he couldn't fix it) and told us the guy he recommended is the same way. We've got our fingers crossed. Usually my husband does our car repairs, but he hasn't worked on 4WD problems before.