Ford Repair: 4x4 light flashing, rear differential, drive feature

Question
I just brought my '02 Explorer home from having the transmission rebuilt.  Now, the 4 wheel drive feature is not working and the "4x4 High" light is flashing.  There is no response when you try to put the vehicle in 4x4 high or low using the buttons and the 4x4 drive doesn't kick in automatically when driving as it should.  The vehicle has never done this before.

We had a really bad experience with this mechanic.  It took 2 months and quite a bit of back and forth to get the transmission working properly.  I know you can't diagnose the problem exactly, but I'm just wondering if the problem be caused by something done incorrectly with the transmission or is this likely just a coincidence?  If the two issues are probably not related, I would rather just go to a different shop because the experience was so negative.

Answer
entirley possible this is connected but before i point blame. on the rear axle of this vehicle directly in the center of the rear axle, you should see a 2 wire connector going into the rear differential. be sure this is connected. this is the speed sensor. from time to time it gets left unplugged also on the side of ( driver's side ) the transmission there are multiple connectors, look for anything loose or disconnected. there should be a couple two wire connectors. my best guess is something got left disconnected. check these and get back to me and i will help you further if needed.. take care... -b-