Update on the wiring for this mod:
I converted my crudely drawn and often-modified wiring diagrams from chicken scratch on smudged scrap paper into an Excel spreadsheet so you could actually read the info. Some of you don't have Excel so I also saved a snapshot of the data as JPG images which you should be able to zoom in for viewing or printing on a color printer.
First a disclaimer: I am not a Toyota engineer, factory technician, or a miracle worker. I do know quite a bit about electronics and I have learned a lot about NAV hacking from the web and various experiments over the past few months. Like the real Wile E Coyote, however, my projects often involve significant risk and more often than not they end in partial or complete disaster so I experimented on my own truck with great caution. Before you attempt a similar project you should consider that a new NAV unit, JBL system, ECU, combination meter, etc. could set you back thousands of dollars at your local dealership if this info is wrong or if you botch the install. Just like the Acme Company I offer no warranties or guarantees whatsoever. This information could be inaccurate or incomplete so proceed at your own risk. You have been warned.
Wiring diagrams for this mod in Excel
Toggle-Switch panel wiring diagram as JPG
AV inputs wiring diagram as JPG