2008 2500hd 4 Lo Problem

[rasnicb]

Hello!

I have a 2008 GMC 2500HD, 6.0l, crew cab, long bed, with about 8K miles. I just recently tried to use 4 lo and found it to be slipping. It used to be pretty snappy. I have to accelerate hard just to get it to move. Its very similar to a slipping clutch in a manual transmission. There are no problems with 4 hi or while in 2 wd. I took it to a dealership and they claim nothing is wrong becasue the computer is not telling them anything. They say that there is a TSB for a seal issue with this transfer case and are ordering parts to fix (even though they aren't sure of the probelm). I have a bad feeling about this one. I dont want them taking something apart if they are not 100% sure they can fix it. Has anyone heard of, or had this 4 lo issue happen?

 

Any help is appreciated.

 

Thank you!

Brian

[BrockwayMT]

It can't be the transfercase. 4L is a dog clutch. You are in high, low, or neutral. Could have something do with the torque management in the engine and transmission controls. Also be advised that some vehicles with drive by wire alter the throttle curve so the engine throttle is less sensitive to the pedal in 4L. This is to prevent bucking and spike loads on the driveline.

 

Manual shift NQG or electric shift NQF?