My 2001 2500HD with Allison transmission isn't shifting right. It doesn't seem like there's 1st gear or the higher gears. The shift indicator is random from p,r,n,d,2,1 and sometimes blinks. It also clunks when going from forward to reverse. Traveling on road you can go approx 45mph @2500rpm. Started when trying to get unstuck in the snow. Only has 23,000 miles. Expecting the runaround from the dealer because 3year warranty up 5 months ago. Anyone with any advice/insight? Thanks so much!

Sounds like it may be in "limp-in mode". Make sure the fuse isn't blown, and you didn't break any wires in the snow.

Hey there,

Maybe take a look at this thread. Sounds like the same thing you are going through.

http://www.automotiveforums.com/vbulletin/t360508.html

Sounds like what happened to me. The switch is all mechanical. No circuit boards at all. My switch had water dripping out of the seams.

If you do this, open up the old switch, you will be amazed.

Just be carefull of pulling out the wire harness's. That is the hardest part of the job. I had to break the plastic to get the harness out.

Replace the park nuetral saftey switch (located on the drivers side of the trannie.

$175 from the dealer. About 1 hour of labor. Worked for me. Yes, there is a God.

Please post your results.