Basically whats happening is it won't shift in to any of the four wheel drive selections. you can hear the motors trying to engage the lights all blink and then it goes back to 2wd. Took it to a trusted mechanic and he says its gonna be about a thousand dollars becasue mine has all wheel drive its not that easy to fix and something has to be programmed. Mine is a 2004 chevy trailblazer 4.2L V6. dont wanna dump a thousand dollars into this thing. sounds like i need a encoder motor which i have found this part online for 200 dollars.