I have a 2004 chevy 2500 hd that has 97k miles on it i just bought it 2 months ago it has been running great until today i was driving it and all of a sudden it started making a whining noise and then the transmission started shifting intermittenly when it does shift it shift just fine and smooth but it wont shift all the time ??? Does anybody have any ideas of a problem or has anyone had this problem before any info would be appreciated thanks ! Also it has the 6.0 l gas motor thanks ...

 

check and post the dtc that have set.

check the trans fluid level and condition. If its brown and smelly your into a rebuild.

 

What is the dtc im not sure what that is ?

 

Diagnostic trouble codes.

That 'whining' you're hearing is nothing more than pinion noise when it drops down into 2nd gear.

Pull the codes and let's see what the heck is going on.

Allan

 

Having a similar problem and got P0894 code. It started shifting hard though. turned off and back on it was ok for a little bit then the check eng light came on, started shifting hard again and thats we checked code. Just bought this truck about 3 weeks ago.