TROUBLE WITH MY 4x4
 

Hey got a 2000 GMC sierra 1500 sle 4x4 with the 5.3 and my four wheel drive stopped working all of a sudden I went to store came out and looked at my dash and the service four wheel drive light was on. I look over and my buttons are still lighted up I try and put not in four wheel and all they did was blink but wouldn't go in and then they shut off and have came back on I replaced the push button switches and still nothing I had code read and it came up c0308 so now I am curious on what to do I was told it could be the tccm or shifter motor on transfer case if some one could give me some advice that would be great I took my tccm out and am think about trying a different one but they are 300$ is there anyway I can test it or has anypne else had this problem guess just looking for some helps so don't end up buying new parts that I don't need

99-02 have the most problems with the switch itself.