I REPLACED THE TRANFER CASE MOTOR AND SELECTOR SWITCH FOR THE 4 WHEEL DRIVE AND STILL DOESNT WORK ON MY 2008 GMC ENVOY DENALI AND SUGGESTIONS ON WHAT COULD BE WRONG?

It could be an electrical problem or a mechanical problem in transmission or transfer case. does it shift into 4 wheel high okay

Not sure about some of the codes you have but looks like you may have traction control / stability control issues. The C code is a chassis code and they are really unusual. You may want to have those codes done again because my machine does not list body codes for some of those numbers. P codes yes, B codes no. But just a comment. If you ran this vehicle with all the wheels off the ground (on a lift) you will get every kind of weird code and light you can imagine. The traction control and stability control computers are very sensitive to issues that don't make sense to them. Running with all four wheels off the ground makes them really confused.

rough guess is that there is a connection that is not properly connected

It might, as well as the speed sensor and ABS system.

If you have the selector dial, you will have to pull the plastic cover from the console. Plug in new selector switch and hope that it works out for you. I have a 2004 and it doese not look too hard. Be careful and not crack the plastic.cover.......

may have a bad switch or selector motor, common problem on these trucks,

check the transfer case selector motor, they go bad and thats what happens, no 4wd and no other lights on switch because its not doing any changing of the tranfer case, to test remove motor ground it and with connector connected, try to switch to 4wd see if motor moves, you can use a test light to make sure its getting power, hope this helps.

Advice only: DO NOT DRIVE have towed to transmission shop. Had jeep do this once...don't risk it?

Envoy 2002 2008 Workshop Service repair manual
My personal suggestion would be to go for these repair catalogs. I know this website reliable-store that i used to buy them from, and they sold online it was very good manual. Go ahead, I bet.

i would not suggest driving it u can start by replacing the selector switch as this is the cheapest thing to replace my switch was bad and made mine stay in four low please rate my advice