4WD question

Hi my name is Corey, I recently just got a 2004 Chevy S10 crew cab ls and I am having an issue with my 4hi and 4lo. It will engage when the button is pushed, but nothing happens. What causes this issue. I also have a check engine light on and was wondering if the 4wheel has a sensor that turns that on. The miles is about 166,600. I checked all fluids and they are normal. So does the 4wheel have a sensor that kicks the check engine light on. Thanks for answers, I really need them. The check engine light that is on, is not blinking, so I'm curious for help with getting answers.

No the 4wd TCM dose not throw codes to the main computer ECM and you need a special GM scanner to read the 4wd codes if your having problems with it. Just go to Auto zone or Oriley's and have them read the check engine code. It has nothing to do with 4wd. It is a different problem.