Hello once again guys. So today I realized I may not actually have a working 4x4 system. The other day in the snow I was in 4hi and put in reverse and backed up the way it should. It actually left ruts where the front tires were where you could see the front tires dig down to the cement in the parking lot. Although today in about seven inches of snow in the same parking lot I noticed a loss in traction. A purposely pulled into the fresh snow at the end of the lot and hung my head out the window and hit the gas. The front drivers side tire did not spin and I sat there spinning the back tires. I eventually got it "unstuck" with a little rocking and continues through with no problems. The lights on my 4x4 indicator switch have never fully worked. They seem really dim sometimes and sometimes while driving they get real bright. I have pulled the dash off and plugged them in a little better without helping thay problem. So im not sure if the switch is just bad. Someone also toltold me when engaging 4x4 it will clunk almost when it engages. And it has never done thay. I hear am the switch click and that's it. Any suggestions. Can it be the switch or is it something under the hood. Any suggestons would help. Thanks. Also it is a 99 tahoe LS