I have a 99 ranger 4x4 4.0 ext cab, I just replaced my ball joints and ever since then my 4 wheel drive hasn't been working. I checked to make sure the hoses were back on good and looked for craks and didn't find any. The 4x4 worked fine right before I changed the ball joints. Does anyone know what could be the cause? Is there a seal or O ring i need to replace after the hubs are taken off? Thanks for the help.

Jeff

 

You could be on the right track. There are a few things you need to consider. This TSB has some ver good PVH diagnostics:

 

Did you remove the black hub assembly? This is a black cap that has gears on the bottom of it, slides onto the hub. Put your finger inside the assembly and push it in, the white plastic part inside. This should lock the gears together, the inside gear will not turn. Push it again and it should unlock them, you can turn the inside gear. When you put them back on you have to make sure one is locked and the other one is NOT. I had this problem when I changed my hub bearing, this is how I fixed it.