Service 4wd light

On occasion,the "Service 4wd" warning light on my 99 Silverado 4.8 comes on.I cant give you an exact circumstance that makes it happen,but is it as simple as changing fluid/filter? Maybe low on fluid?

Most likely the circut board inside the switch has some solder points that have cracked , it is a common problem with those switches. Wish i knew about this forum back when i had the same problem , it would have saved me about $150 to diagnose that it was the $85 switch. Supposedly you can take the switch apart and resolder the spots where it is cracked.

I just purchased the switch at dealer and let them install it. Total cost was $60