Toyota trains their techs so they expect the mechanics to know most of it. Certain TIS pdfs walk you through basic terms and techniques for navigation, wiring and the like. Specific pdfs like the P0401 walk you through the process for that diagnosis: The blue box above is a link to another doc. Those links only work online with the TIS access. But you can download that doc and others with one two day access or sometime find them here. From P0401 pdf Some basic screen captures You pick the ecu you need above. Engine and ECT for P0401 Once you have picked an ecu you can do Data List for live data and then pick a few points to monitor. Then Active Test ( this capture is Main Body). Sometimes you need Utility for things like Inspection/Maintenance Mode.
