It will display on dash (service four wheel drive)?

i had bought this truck straight off the lot new, i have been the only owner and have had noting but all problems. first this truck has been in the shop for three months at 27000 miles gmc replaced the transmission 3 times, then i replaced a front wheel hub at 34000 miles then a cv joint at 38000 miles. i no longer have factory warranty. i now have problems with my 4 wheel drive 44000 miles. it will display on dash (service four wheel drive), then i lose the lights on the selector for 2high, 4 high, and 4 low this problem comes and goes. Do you have any solutions i might look at?