I have a 2002 (Sierra) with a NP246 xfer case. I can not get the truck to engage 4wd. The local mechanic claims $2000 to fix it and doesn't know what the problem is. I can't help but believe there is a simpler and cheaper fix...My '05 Silverado needed an encoder motor sensor ($80) and I re-soldiered the connections inside my 4wd dash switches. I am hoping there is a common problem with these and someone may have the solution...