The AW tranny is used in lots of different cars with different bhp and torque values. In order to mate the tranny output to the engine output, software is used. The software is developed in a lab with ideal conditions.

When the cars get used with thousands of different driving styles and driving conditions, updates are then created to match so the tranny doesn't break. The updates are permanent, they do not disappear when the battery is disconnected.

When the engine computer is updated, this might also have an effect on the TCU which could have a positive effect on the way a tranny works. Most mechanics that I know will apply multiple updates when ever a car is in need of a programming change, like security. Just bringing the ECU up to date, hopefully saving a future date with the shop to have more updates applied.

There are more computers on the new Volvos than my 1967 has fuses! And all of these computers must be 'in sync' for the entire car to operate smoothly.

Klaus
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Cynthia Amendt, RIP