Question

Problem: 2001 Silverdo 4x4 with "Service 4wd" displayed on dash. The indicator light comes on and the truck stays in 2wd. Then once I shut the truck off and turn back on the 2wd/4wd switch does not light up except for a small blink when you initially turn the key. Other than that the switch does nothing what so ever and it feels like the truck goes into 4wd hi. I've solved the problem by disconnecting the battery overnight and reconnecting but both times I've done this the problem reoccured. I have read posts that say to replace the switch. I have a friend with a scanner but there were no codes relating to the transfer case or any of the sensors. I cleaned some grounds behind the drivers side tire and no luck. Should I replace the switch? Or does it sound like there is something else wrong?