[wileetundra]

Update on the functions of this mod:

I have been testing this mod over the past few days to make sure it holds up under all sorts of different usage scenarios and combinations. Everything works fine however I found two glitches which I am working to resolve. Any help or alternate solutions would be appreciated.

1. When the bypass switch is used to enable the NAV functions while the vehicle is in motion, it works like a charm and all the functions are immediately made available. Unfortunately they only stay enabled for roughly 30-40 seconds and then they are disabled again even though the switch remains in the bypass mode. I can flip the switch back to factory mode for 5 or more seconds and flip it back to bypass mode for another 30-40 seconds of functionality but it always resets eventually. I did a lot of research on this and it appears that the NAV unit is looking for a consistent speed pulse signal from the CAN network. When the bypass switch is first thrown the pulse signal disappears completely and the NAV assumes you stopped so it enables all the functions, but then it eventually sees that you are still moving (probably from the GPS) so it disables the functions again. I assume the 30-40 second delay is programmed into the software to give the speed pulse signal enough time to return before reverting to the GPS speed input which is adequate but generally less accurate than the pulse method. I tried working around this by feeding a fixed voltage into the pulse circuit on the NAV and I varied the voltage to match the real pulse signal when the vehicle was stopped, however this doesn't work any better than removing the pulse signal altogether. Further research indicates that the CAN network is most likely broadcasting a digital pulse signal at the 1hz level so there isn't a quick or easy way to duplicate that (at least not that I am aware of). You can purchase pulse generators for various NAV systems but they are designed to provide the true vehicle speed and not a fake pulse. I am currently thinking of ways to build my own pulse generator or dummy circuit which will emit the same signal as the valid pulse when the vehicle is stopped. Before I do that I am going to try connecting a new input to an unused pin on the NAV which I believe is normally used for the Parking Brake signal in Denso NAV units that are made for other vehicles. It is likely that the Parking Brake sensor circuit and software is present in our NAV unit but Toyota didn't include a wire or pin for it in the vehicle harness since they don't use that function in our vehicle configuration. If this works then the NAV is likely to enable all functions when it sees the Parking Brake signal, which should be easy to emulate since it is most likely just a line to vehicle ground.
2. When enabling the video input while driving it works great and you can watch the tailgate camera, DVD player for passengers, or whatever. While the video input is enabled, if you select other functions like the MAP, Audio, or Phone then the video screen disappears to show the selected functions. Unfortunately I can’t find a way to switch back to the video signal again unless I re-toggle the video input switch which is easy enough to do but it is a pain especially if you get a lot of calls while driving. This could be greatly minimized for my usage scenario if I could find a way to disable the automatic switch to cell phone display when a call is made or answered, however I haven’t found a setting for that in the NAV. There is a setting not to auto-switch the display and I have it turned off but the phone screen still pops up whenever I make or take a call. I am not sure what to do about this one but I am sending away to Acme for a planning book.

Also, good news on the “Check surroundings for safety” disclaimer mentioned in the original post above. I downloaded a binary file editor and scanned every file on the NAV DVD for this text string. The only file which contains the text is the ever-popular Loading.KWI which is the main firmware. I was able to edit the file to replace the text string with a blank text string (all spaces) so now I just need to burn a new NAV DVD and see if I can get the modified firmware to load. If it works as I am hoping then the disclaimer will now be invisible. Any other ideas or tech info for this or related issues would be appreciated. I can also use some testers to scan the wiring info and let me know if anything is missing or confusing. Pictures will come soon, I have to take some more since I had the focus mode set wrong and many pics taken during the install did not turn out.