Allison Transmission 29540479 NSBU Switch Kit 2001-2005 LB7 LLY 5-Speed 2 Plug
One of the most common problems with the Allison transmission is failure of the Neutral Safety Back Up switch. This switch is the dual plug style that can be found on any 01-05 LB7 or LLY. We always recommend to visually checking the switch on your transmission before ordering. This NSBU switch can be installed with common hand tools.
Some of the common symptoms of failure are listed here
No start condition
Gear shift indicator on dash not following properly
Trans stuck in limp mode or fail safe
DTC's set indicating pressure switch codes