Blinking 4x4 light

I recently purchased an 01 Passport. The 4x4 light blinks and I think the 4x4 is not engaging. I took it to a local shop and was told that it could be either the transfer case or the transfer case motor. I told them that I had a dealer 3,000 mile warranty that covers motor & transmission. It sounds complicated, I was hoping it was something simpler. Should I take it to a transmission expert for a 2nd opinion? I'm a 1st time auto forum member. Was else can it be?