Allison 4000mh with Cat C13 problems

[num1dgh]

Has anyone had problems with the Allison 4000MH transmission sticking in gear with the Catipilar C13 motor. On our last trip, I put the transmission into 4th gear going down a grade and it stuck there. I had to pull over, turn the motor off (because it wouldn't go into any gear or neutral), and then restarted it. It hasn't occurred again in the last 300 miles, but I think there is something going on. Any ideas?

[Bigbluedog55]

Hi,
My Affinity with the 4000 Allison did something similar, went into 1st gear and stayed there awhile. Couldn't shift it at all. Then for a while it worked fine. Then wouldn't go into reverse, neutral or anything, then worked ok for a while. Usually required a shut down and restart of the engine to work again.
So.... I took it down to the CAT / Allison dealer and they hooked up the reader and it spit out a fault, and it was a bad output shaft speed sensor, I think. Anyway, $280 later all was swell. No problems since.
Seems, so the dealer said, that if the transmission doesn't know the speed (rpm) of the engine, it won't let the transmission ruin itself.
Anyway, that's my story and I am sticking to it.
Luck,
Bob

[num1dgh]

FYI . . . took it to a CAT service center. They found NOTHING wrong and diagnosed a "ghost" in the system.

Spooky.