about a month ago my buddy n me were using my 06 duramax to try to pull out a stuck vehicle. I backed my truck up to the vehicle close enough to put a tow chain between, while remaining on somewhat dry ground. I was in 2 wd and pulled the chain tight and began to pull on it..this aint gettin no where so i pushed the 4 hi button and kept trying. no luck . so then i put it in neutral and pushed the 4 lo button let the light quit flashing and then put it in drive. frustrated with the lack of success in pulling out the stuck vehicle, i gave it hell, u know give her some gas. during rpm increase i heard a really loud grinding noise from underneath, sounded bad. then both the brake lights came on.. whats up with that?? now my truck makes a LOT of driveline noise in 4 wd.. did i F something up? Help i feel like an idiot

In 4 low you should have took it easy, it would have pulled no prob, i pulled an avalance sideways up a hill through 6 inches of snow in low range, you might have hurt the gears

damn i hope i didnt f it up too bad. the only thing i can think of is that i didnt let it roll into 4 lo. i put in 4 lo when i was motionless. ?? but i dunno why the brake lights cum on

Take it back to the dealer and play stupid with them, let them repair it. Next time let it roll a little with no throttle so the drivetrain has time to mesh/line-up for proper engagement.

I think i will. Thanks for the reply.

Sounds like traction control is kicking in when the wheels are spinning. Could be applying the brakes to try and stop the spinning. Also sounds like it wasn't fully locked in when you stomped on it.

4x4 low does not like to be rushed. you need to make sure it's engaged before you lean into it really hard. With the old manual shifts you could tell, because when you tried to force it into 4 wheel low it would just grind like crazy and not engage. Agree with the play dumb and take it to the dealer senario. Let them figgure it out.
Good Luck

Using 4 low it is required that you shift the transmit ion into neutral before pushing the 4low button.

That is what he said that he did. Gears were probably not engaged properly. Don't know about the brake light though.

thanks. hey i had put it in neutral before i pushed the 4 lo button. i took it in this morning got it back this afternoon. they said they couldnt find anything wrong. they said it may just be a warped front driveshaft or a cv is going out. jackasses, thats bull sh** they dont ever do anything to help ya. im gunna take it to another dealership.

find another dealer again play dumb. that is bs why would a dealer tell you there may be a problem? Can they replicate it? if they can replicate the problem, tell them dont tell me what it maybe is find it and fix it.