What's new

LLY Allison Issue


Red Skull Member
May 19, 2020
Member Number
Galveston, TX
I’ve done quite a bit of searching, but haven’t come up with much. While driving, typically at higher speeds it feels and sounds like the transmission disengages, almost like its been put into neutral.

It doesn’t make much sense, and has never lasted long enough to trigger a CEL.

The exception, of course was when my wife was driving it. The details from her aren’t the clearest. It went into limp mode and would not drive. I was able to clear the CEL and it’s hasn’t done it again. I’ve attached the codes.

Any thoughts or direction are appreciated.

Last edited:
My LB7/Allison started doing similar things last winter. All kinds of weird codes and going into limp mode. From what I have read a lot of times it is the connection to the TCM, The pins in the connector back out. Mine is pretty much a plow truck so I haven't touched it. Probably should one of these days before it starts snowing! https://www.youtube.com/watch?v=9yN5FzWwnRU
01, 8.1, Allison, Driving in deep snow I managed to pack the drivers side connector at the transmission full of snow, let it sit in the shop for a day then took a hair dryer to it. Cleared the codes and no problems since.
Top Back Refresh