4wd Does Not Engage

[treefort]

Hi all,

 

I have a 2008 2500hd Chevy. The other day at work I got stuck in some deep snow. I had to rock the truck back and forth in order to get out. But, the truck had a second pause when stepping on the gas, so in 4wd, I put my left foot on the brake and stepped on the gas a little with my right foot until it started to move, and then released the brake. While revving it with the brake on I heard a clunk and ever since my 4WD has stopped engaging. The 4wd light comes on as normal but the back tires only spin. When I put it in 4 low the truck shifts like it is in 4 low but again the rear tires only spin.

 

What do you guys think is wrong? Are there any tests I can do to isolate what is broken? There is no check engine light on so I am pretty sure the shift motor is fine.

 

Any advice is greatly appreciated.

 

Thanks,

[roperninja]

Transfer case engage servo/solenoid?

[tyhuck]

Could be the electronic front diff actuator. I know on the s-series trucks they had alot of problems with this because it was opperated by a rubber vacuum actuator. I beleive our trucks are all electric, but from time to time, the electric actuators can go out. This would cause everything in your 4wd to work, except the front diff never engages, so no power goes to the front wheels. Thats just a SWAG though.

[gmtech4]

you have 5 yr powertrain warranty left??

 

if so ,,,not your problem

 

yes it has codes and data to read ,do not throw parts at it if warranty is done

 

get it looked at .....could be a bunch of stuff

[treefort]

Thank you all for the replies. I just wanted to know if there was anything I could test before it goes to the shop(Monday morning). I will look into the front diff actuator.

 

Thanks again!

[treefort]

Brought my truck into GM today and they found a broken shift collar and fork. And the splines on the front axle were shot. Thankfully it was covered under powertrain warranty. Otherwise it would've been $1600.

 

Thanks again for chipping in.