Navigation Input Override (Speed Sensor Bypass)

I dont understand something - what happens if you simply bypass the speed sensor altogether? As far as I understand, dead reckoning only improves accuracy slightly - we wouldnt suffer any real consequences by simply by passing the speed sensor, would we?

Im saying because - In my mom's '09 Sentra, I had a TOMTOM ECLIPSE AVN4430 installed (http://www.eclipse-web.com/us/avn/avn4430overviews.html) and we simply bypassed the parking sensor and speed sensor, and it works perfectly fine. How is the Prius different?

 

Because the Prius' navigation relies much more on the dead reckoning.

When you bypass the sensor, the navigation becomes HIGHLY inaccurate, to the point of being useless (for me, at least) as it displays your previous known location and updates every 30 seconds to 2 minutes, causing huge jumps in the map.

VERY easy to miss a turn that way. I recommend against doing this.

 

I was talking to a service tech at the Toyota dealership, and he mentioned something about a software override for the NAV system. But when I asked him if he could do it for my 2010 Prius, he suddenly had to go get back to work.

"IF" such a software override is possible, I'd much prefer that to 'tricking' the speed sensor.

Of course, that means the driver would have to use the honor system and let the passenger touch the controls.

 

Please don't get me wrong...
I think your solution is very creative and useful.
I also liked your auto headlight hack. (ordered the kit myself, thank you!)

But given the service tech mentioned there is supposedly a software mod, I hope it is only a matter of time before it escapes into the wild.

Also, I tend to overkill on projects I tackle and taking the 'difficult' route is normal for me...

 

A similar solution seems to have been found for Tudras of that time period as well.

2007 Toyota Tundra Installation Report by WileETundra

The fellow even sells them assembled for those who don't like to solder. I wonder if the same technique/device would work on the '10 Prius NAV?

 

Glad that helps - I figure if you're going to do the prototyping, the least I can do is help with the research

 

If the service tech is correct, surely he would be referring to a hidden system setting. The question is; How do we get into the hidden controls?

 

Don't know. But I talked with the sales manager yesterday, and he said he watched his service tech change the settings on a Prius in just a few minutes. When I asked how, he said "It is on the web." So I wonder if he thinks the 2010's act the same way earlier hacks work... And we know that the 'old' hacks don't work on the 2010's.

 

The sales manager is probably thinking of the section 6-2 customizable settings and just doesn't know that the NAV lockout isn't part of that.

 

Per TIS, its a digital signal, square wave, 4 pulses per revolution of the tire.

 

I've confirmed that cutting this wire and injecting a square wave of the right frequency does allow access to navigation, phone and voice features which are normally locked out above a few miles/hour. Seems the algorithm is like this:
speedSignalFrequency > 6.04Hz : begin lockout
speedSignalFrequency < 4.80Hz: release lockout

So I tried a 3.3Hz 0 to 12V square wave injected into the Nav unit side of the violet wire hawkmoon77 mentioned. Driving around for a while, I found it to give continuing access. The only side effects I've found so far are:
1) The position on the map lags behind where you really are as you're driving but every 30 seconds or so it jumps to the correct position. So it seems it dead reckons at ~2mph for a while, then the GPS notices that deviation from GPS position is too large and over-rides the dead reckoning.
2) The consumption bars on the bar graph are not 0 like they were for the 2004, but I think they are lower than the correct answer. Likely it's using the speed signal for distance instead of the GPS signal.

 

Actually I think the consumption bars are OK. It was a little hot today and I think the mpg were lower due to the A/C.

 

sounds like some of you are getting close to finding a way to defeat the system. keep us posted, i would love to be able to have the passenger key in input while i am driving.

thanks for the hard work!

 

Fantastic news! Now all we need is someone to put it together into a little plug-n-play box that us non-electronic types can buy for a reasonable price and plug in

 

How about a microcontroller that accumulates the pulses, feeds the system no more than the 6.04 Hz, and bursts the accumulation every 15 seconds? How high a rate can the system accept? Does it dim out with a very short burst?

 

Now that's what I call an elegant solution! If the reaction time of the system was say 0.1 seconds, you could accumulate the pulses long enough to enable the input, then feed them back on 0.09 second bursts of very high speed, perhaps even the equivalent of 200mph or something. If you keep the bursts short enough, you might actually be able to keep it out of lock-out mode indefinitely without even losing the dead reckoning ability. Very clever idea!