I think meliftman is using the term 'trademark law' to indicate 'all intellectual property law', and (IANL) I think it is proper to refer to the law governing manuals and software as 'trade secret' and/or 'copyright' (mainly copyright). But he does have the correct idea about someone paying the license fees to own the right to distribute the information and software.
AND, actually what was done in the automotive world was to create an 'open standard', where the copyright for the standard is owned by some organization that allows it to be used/licensed without added fees, like the IEEE or in the forklift world, if not the IEEE, then ITSDF.
I think it is also a great point that 90% of what breaks does not require a laptop to fix, some people seems to stop hearing right after the "on this truck you need a laptop" and don't hear the "to only do about 5 things".