Allison 1000 02 workhorse w22

You may just need a firmware upgrade to your transmission control module. Any Allison shop should be able to see if your control module is up to date and correct it if it is out of date.
Also your engine control module, ECM, may be feeding incorrect information to your transmission.
Find a shop that has the proper diagnosis equipment and they should be able to pin point the problem without throwing expensive parts at the problem while you foot the bill.

Thank you.

Let us know what you find out.
Bill

Read the codes from the check engine light. It could be the engine telling the trans to unlock because it senses an issue.

Really need to know what the Check Engine Light code is.

It may not be a transmission problem at all.

my 2006 w22 Allison did the same thing 3000 miles after buying new was told the connecter at the module was missing insert did think that was the problem being I own a automobile shop waited 2 weeks for part when I got it back did the same thing decided to fix my self found torqe converter soliniod was reading wrong resistance droped the pan and replaced it in my driveway have never had a problem again you need to plug a scanner into obd2 plug that has workhorse solftware and read code will probably have a po700 code and another code in the 700 hundreds

This has all been good information and I’m very thankful
For your reply’s.
I did talk with a Allison service guy that has the proper
Scanner for the transmission.
He said you can maybe find the problem by changing some parts
But it could be that it’s not anything but a tweet or program change
Upgrade ECT.
$150 to scan it and $150 pur hour for labour.
It may be in my best interest to limp in to his shop and give him a shot at it
I’ll try to let you know how it turned out.

I had the transmission check and no codes showed up
I tried a can of Seafoam trans conditioner and it’s
Not locking and unlocking except on occasion.
I’m in the Rockies now and I think I can make it home.

It's always good to be able to make it to your home base to deal with a problem. Hopefully it will be an uneventful trip. You can always manually shift it out of OD in those occasions when you do not want the transmission to shift in and out of OD on it's own.