Allison Tranny Problems

[cweeks]

New to the forum and own a 2004 2500HD with 145,000 miles. Tranny seems to be shifting into neutral and when you decelerate seems to shift back into drive. Problem was very intermittent but now happens constanltly. SES light has come on but not every time. When it has come on the codes have been a 5th gear and 3rd gear shift alarm. Some times when this happens and you put it in reverse it flashes and no movement. Put in park shut truck off then seems to reset itself but continues to drop into neutral. Would this be a nsbu problem. Any help would be greatly appreciated.

[More Power]

New to the forum and own a 2004 2500HD with 145,000 miles. Tranny seems to be shifting into neutral and when you decelerate seems to shift back into drive. Problem was very intermittent but now happens constanltly. SES light has come on but not every time. When it has come on the codes have been a 5th gear and 3rd gear shift alarm. Some times when this happens and you put it in reverse it flashes and no movement. Put in park shut truck off then seems to reset itself but continues to drop into neutral. Would this be a nsbu problem. Any help would be greatly appreciated.

An Neutral Safety Back-Up switch (NSBU) problem most often expresses itself as a "PRNDL" display issue. When was the transmission last serviced?

Jim

[cweeks]

Jim
The internal and external filters and fluid were just changed less than a thousand miles ago. The problem showed itself before this once but has progressed.