The Ranger is actually owned by my father. It is a 4.0 4X4. 98 or 99. When you kick on the 4wd both lights flash. You can hear clicking in the dash. We were origionally told to buy the new module to fix it, but that changed nothing. Occasionally the truck feels like it changes to 4wd when you switch it, but not so much on demand, more like randomly. Works much less often then not. Someone mentioned to us that it could be a screw gear in the transfer case, but I am not sure what exactly they are refering to or how to fix such a problem. Any help is appreciated. Thanks in advance.