"range Shift Inhibited"?

[ImaRoadDog]

Does anybody know what might cause the Allison transmission to fail to go into gear from park and display the message "range shift inhibited"? If I cycle the transmission from park to reverse or park to drive several times it will sometimes engaged, but it is getting worse. Wife just called me from work and said the truck is stuck at the end of the driveway after slipping out of drive. I took it to my local dealer but they are clueless and say they don't have time to look at it (I know, I need to find another dealer). Any ideas would be appreciated as it seems I am on my own. It's a 2004 Duramax Diesel 2500HD, extended cab. Thanks.

[xfiresk]

i have the same problem but now i have a check engine light on too

[unusualmind]

dont know nuthin bout transmissions, but i can tell you that ur dealer sounds like a REAL winner

[ImaRoadDog]

dont know nuthin bout transmissions, but i can tell you that ur dealer sounds like a REAL winner

 

Yes, a real winner. Clearly, they are afraid to even look at an Allison tranny, much less touch one. They totally blew me off. Nothing like being left out in the cold by a GMC dealership that chooses not to work on a vehicle they don't have to because it is out of warranty. Not sure what to do now. Maybe someone else will have better luck with a dealership having the same problem as me and let me know what the solution might be. I've heard it could be the NSBU box or the ignition switch.