Allison 4000

[46490]

How can you tell if there are CPU updates for the 4000 series transmissions - is there a site that you can check based upon serial numbers of the trans?

[dbarton291]

In Service updates for the Allison controllers are only released when there is a specific issue for a specific population of vehicles. It's not like an iphone where the latest software is considered an improvement over the previous software level.
When there's an issue, service bulletins are released to the Allison distributors and dealers with specific instructions which vehicles to update and to which level.
There are a few fleet customers that pay the local distributor to come out and update their vehicles to the latest production released software level for their controllers. It's usually costly and has no noticeable benefit.