Service 4WD
 

I have a 2004 Silverado 1500 z71. I don't know where to begin to start to explain this, but every so often, maybe once every 2 or 3 weeks, ill be driving and my dashboard will spit out "Service 4WD" and then the radio stops and just turns off, all my dashboard lights come on like it just got reset, but the engine will still be running and I can drive normally, besides the whole dashboard basically just reset/ died. I don't know if thats a good explaination, and I have absolute no idea where to start because of how rarely it happens. I think it'll be done and over with, but then it just randomly happens. If anyone has any idea, please god help me. Thank you