Question: I have a 1999 4WD Automatic Chevy Silverado in which the 4 wheel drive service light is on. It will not engage to the 4 wheel drive. I like to know what that would be causing that. I also like to know what kind of transfer case I have as well.Answer: This is a NV246 transfer case and they have many issues. As far as the service 4wd lights, it could be many things. They have dash switch problems, module issues and encoder motor issues. I would start by checking the fluid level and condition of the fluid. The rear case is subject to oil pump rub from the inside and it will create a pin hole in the rear housing and even though you may not have seen the leak it will while driving and run the transfer case dry.If the transfer case is full and the fluid color is still blue then I would suggest getting it on a scanner and see if it is commanding the encoder motor to shift.If the fluid is burnt or low it is more likely that the clutch pak is burnt up and out of range throwing the code and requiring a rebuilt.