I got it! "I agree" killer! Cheap, easy, but...

[naterprius]

So, here it is. The idea is, keep the NAV ECU powered all the time. The mod is easy, fast, cheap, and effective. There is only one possible side affect: increased parasitic load on the 12V battery.

I'll have to double check my wires, but short pin 9 and 18 together, CUT the gray wire, and feed power from B+ to the B+ and the ACC wire. This fools the NAV ECU into thinking the car is still on. It works perfectly. It may be impossible to eject the DVD with this mod in place, though. The only caveat is will this affect the 12V battery (will it drain dead while parked).

Typical parasitic load on a normal car is around 50 milliamps. More than that is considered an error condition needing service.

I have noticed that the DVD drive spins down if left unused for long periods of time. I suspect that the parasitic load will drop once the disc parks. I don't have an inductive ammeter, so I will have to put one in line to check the load. (brosnan, do you have an inductive ammeter?) Check the parasitic load with car off, mod in place right after using the NAV system, and after the drive has spun down.

Anyway, you will need:
1 scotchlock
1 piece of electrical tape
1 wirecutters

-1. CUT the gray wire (leave enough for step 2 below) so that you are no longer feeding power back into the rest of the ACC circuit (feed it only to the NAV ECU).
-2. Connect the scotchlock to jumper the blue and gray wires in pin location 9 and 18.
-3. Tape off both ends of the cut wire so it doesn't short against anything.

Let me know if your battery dies, or the car ceases to function. (Don't hold me responsible if this doesn't work, you take your own chances).

Nate

[DaveG]

I don't have the Nav option in mine, but what's the advantage in keeping it powered continually?

Dave

[naterprius]

Every time you start the car and try to use the NAV system, there's a disclaimer (you have to select "I agree") and language selection that you must bypass. Ironically, it says don't take your eyes off the road, but you must take your eyes off the road to read it.

I have discovered that powering the NAV ECU all the time seems to avoid this.

Nate

[mss]

That is going to be very annoying. There has got to be a better hack. Perhaps strategically placing magic marker on the disk rendering the licence verification unreadable will do the trick, like the failed attempt at CD copy protection not too long ago...

[naterprius]

The best hack would be to crack open the NAV ECU, extract the software, rewrite it, flash it back to the chip. Maybe the DVD itself contains the software? I'll look into that.

Nate

[mss]

I would imagine it is in ROM, which is probably a PROM chip since I believe one of the service updates included programming the ECU.

[Danny]

It's a great start, nate - thanks for sharing it with us. Hopefully the hack can evolve from here!

[efusco]

I have to think there's gotta be a way to keep a much lower power level going in to just the important circuit that keeps the system 'awake' rather than powering the entire NAV system.

The parasitic drain bothers me a lot with this solution.

[naterprius]

Well, I have confirmed that the DVD drive does spin down after some period of inactivity. I'm going to guess that this is most of the electrical draw. If I recall correctly, though, handheld GPS units draw a significant amount of energy; enough that they can't be kept on constantly. I'll check the parasitic load tomorrow to see how high it is after it sits all night. (If my battery isn't dead!).

So far, so good. Turn the car on, the map is there. Very nice.

As far as a real software hack, I found the text from the menu imbedded in HEX ASCII inside "loading" file on the DVD. In fact, all the menus are there. In interesting hack would be change some of the strings and see if they change on the screen. (I'd need a DL burner and some blanks). Maybe I could experiment with single layer DVD until I figure this out.

I suspect it may be written in vxworks; I'll have a friend take a look at it next month perhaps.

brosnan, do you know what kind of processor is on the board for the NAV? TI? Motorola? Broadcom? Maybe I'll crack mine open this week and take a look.

All I need to do is figure out something at the assembly level and put in a jump statement or a nop (no operation) where execution goes to the screen. There may also be a boolean indicating whether the system has been powered since the last access. If so, it could be set to "true" all the time.

So many simple solutions, I just need to figure out the structure of the code...

For now, I'll report back any issues with my mod. By the way, I made mine completely reversible using some spare Toyota pins and connectors. I pulled the pins from the N2 connector, placed them in a new connector, took the opposite of that connector, put in one male pin connecting to the blue wire, which I soldered to two spare female pins that go back into the N2 connector.

Nate

[V8Cobrakid]

.. you guys really know your stuff.. this post is fun to watch