I have an indicator light on my 2004 suburban which says to service the 4wd. Also the lights on the 4wd and 2wd buttons are not illuminating when the car is running (all the lights on each of the buttons come on upon startup). I took the vehicle into my dealer for an oil change and a checkup on the 4wd but received no info about any problems and the car worked fine for a few days after it was examined.

I would contact the dealer and (ASK) them what did they do or found . I'm pretty sure if they checked it , you would have that info on your copy of bill.