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

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

 

Re: I got it! "I agree" killer! Cheap, easy, but

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

 

Re: I got it! "I agree" killer! Cheap, easy, but

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

 

Re: I got it! "I agree" killer! Cheap, easy, but

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

 

Re: I got it! "I agree" killer! Cheap, easy, but

To V8CobraKid:

Hah! I got you fooled...

If I really knew my stuff, I'd post instructions on how to modify the code on your NAV disc to remove the "I agree."

;-)

Nate

 

Re: I got it! "I agree" killer! Cheap, easy, but

Well, in that case, thanks for the compliment. As far as having the right ideas, they come from questions, either my own, or from others. As Einstein put it, the question and the answer are really not different at all, rather the same thing.

For me, this one was: "Every time I turn on the NAV system, I have to push "I agree." How can I avoid having to do this?"

The answer was in the question itself, leave the NAV system on!

My point is, if you think of a question, post it! (perhaps after reading the previous posts to save on the repeats).

Even contributing to the forum in the form of a question is worthwhile, it may provide the answer someone else is seeking.

Nate

 

Re: I got it! "I agree" killer! Cheap, easy, but

Well, I got impatient, and wanted to check the parasitic draw. Without the mod, it's around 20 milliamps (specified limit for a generic car is generally accepted to be around 50 milliamps).

With the mod, it's around 350 milliamps, even after the DVD drive spins down. This level is right at the edge of problematic. I'm uncertain if the Prius' smaller battery has smaller capacity when compared to larger car batteries.

Even if this mod never causes the aux battery to go totally dead, it would likely reduce the lifespan of the aux battery; it would "die for good" at an early age.

I'm on the fence on this one; I may go with this mod anyway.

Nate

 

Re: I got it! "I agree" killer! Cheap, easy, but

Tony, I have now been in 87 seperate collisions since I made this modification. A total of 31 people have died and 47 severely injured. Most of this was caused because the GPS system told me to drive on the sidewalk, so I did, and I have run over quite a few folks that way. A few have been caused by driving on the wrong side of the road. Still others were caused by me ignoring stoplights that were not indicated on the NAV system. The worst one by far (22 casualties) was caused by the time I somehow got the system into "French" mode, and was not given the option to select "English" when I first tried to use the NAV system on that trip. Vou le vou coushay avec moi?

Regardless of this, I am certain that everyone agrees that none of this is my fault, and a lawsuit against Toyota is in order. Perhaps this will encourage the voice command system in the next generation of vehicles to read aloud the legal disclaimer everytime one presses the "voice command" button. This would truly make our society safer.

Nate

 

Re: I got it! "I agree" killer! Cheap, easy, but

Seriously, I've decided to leave this mod in place for a while. To add to the experiment, the car doesn't roll much these days since I'm home on leave with my new daughter. We'll see if I go out one day next week and the battery is dead.

350 milliamps is too high, but we'll see what the detrimental effects are.

Nate

 

Re: I got it! "I agree" killer! Cheap, easy, but

Drove the car last night for the first time since implementing the mod. Started right up, no issues. That makes over 40 hours plus all the extra power I drew messing around for a few hours before.

Not bad. Maybe the draw fell quite a bit after it sat for a few more hours. I'll keep everyone posted.

By the way, with all this talk about voiding warranties, this one could void your warranty on your aux battery; that is, if your car dies, and needs to come in for service, it's likely because of this mod, and you might have to pay for the repair.

Nate