The software in the on-board computer is not available as a retail product. Only certified mechanics and dealerships are permitted to obtain the software from the manufacturer.
The tune up of a rig's diesel motor is done on three main areas on the old mechanicals, and is done through the on-board computer on the eletronic controlled motors. The fuel system, turbo system and cam/crank timing are the three areas which are checked...and set if out of spec.
On both mechanical and electronic motors there is a leak test done on the ram air ducts. On the mechanical motors the fuel injection pump motor's access plate is removed and dials are used to check the fuel cervo setting and the rpm setting (you basically set fuel cut-off points on these two items.) On electronic motors this is done through the on-board computer. A motor's horsepower and rpm range is controlled through the amount of fuel allowed to be delivered through the pump motor.
The term "tune-up" is used, but it's more of checking the proper operation of these three areas on a diesel motor. The on-board computer diagnostic is not a tune-up, but a check of information retained within the computer retention file...and a resetting of those codes upon retrieval of the stored data.
Hope this answer your question.
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