Every manufacturer has software its own dealerships use to talk to the computers inside its vehicles. Toyota's is called Techstream — also written as Global Techstream, GTS, or GTS+, which are the same tool under newer names.

It is not a code reader. It connects through the vehicle's diagnostic port and speaks directly to each control module, which means it can retrieve records Toyota keeps for its own purposes rather than only the data federal rules require to be published.

That is why it matters in crash work. On a Toyota or Lexus, some of the most useful evidence sits where only the factory tool can reach it.