Hello all, on the way home tonight my 2003 l322 td6 started vibration then a whining sound , it's only stopping in one gear , not changing up or down . I've tried it in manual and it's the same but indicating different gears although not changing gear.
Help needed . I've plugged in my new icarsoft diagnostic tool but nothing comes up.

Mmmmmm it sounds like the dreaded GM box has failed. If it is the original box still, than it sounds like it lasted very long. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

The car has done a little over 200,000 miles , had the gearbox rebuilt at 145,000 miles , maybe they didn't do a good enough job ?

The GM 5L40-E Automatic Transmission: Common Problems

https://axleaddict.com/auto-repair/The-GM-...n-Problems