DIY: All NAV Functions All The Time without Firmware Downgrade!

[wileetundra]

The factory NAV unit in my 07 Tundra is great but it has an irritating and poorly-designed safety feature which disables many of the functions and on-screen buttons whenever the vehicle is in motion. This is done presumably to prevent the driver from being distracted while driving, however it doesn't take into account that the front seat passengers will want to use those functions (especially on long trips). This is a common problem on many vehicle NAV systems and there are literally dozens of threads and thousands of posts on forums all over the web with vehicle owners seeking a solution to enable all the NAV functions while in motion.

For the 07 Tundra you can purchase or burn a modified firmware DVD which will enable the functions, however this can be expensive, the burning process is tricky and requires a specific hardware / software setup, the bypass function has to be initialized every time you start the vehicle, and you will lose the bypass function if you upgrade to the newer factory firmware when it is released.

The ideal solution was to find some type of hardware modification which will work with most NAV units and won't be tied to a specific firmware version. Obviously I wanted something cheap, fairly easy to acquire, easy to install, automatic to use, and reliable. I came up with the perfect solution after hundreds of hours of research, firmware evaluations, vehicle wiring tests, and some basic electronics tinkering.

The answer was to build my own speed pulse generator which would replicate the signal from the Tundra at 1 kmph so that the functions would all stay enabled all the time regardless of the firmware version. The parts cost about $15 and it works like a charm. You can see the photos and details in my latest installation report by clicking here and then scrolling down to report #16 - NAV Speed Pulse Generator.

Enjoy.

[Jer]

Very interesting. Great work as usual. I'm interested but have one question: When you do the hybrid disc with the older loading file injected it will enable the controls accept for the phone functions and a couple other small things. Will this single mod allow for everything to work while in motion??

[wileetundra]

Originally Posted by Jer

Very interesting. Great work as usual. I'm interested but have one question: When you do the hybrid disc with the older loading file injected it will enable the controls accept for the phone functions and a couple other small things. Will this single mod allow for everything to work while in motion??

Yep. You just connect the speed pulse generator with the toggle switch and all the NAV functions work all the time. No need to use the old firmware, burn any DVDs, or lose any functions. It is not dependent on other mods at all. I suspect it will also work with the new 7.1 firmware which was recently released.

[redhawks1]

ok wilee i give. how can i post that i figured out how the ashtray works and your making Uranium PU-36 Explosive Space Modulators for the truck .
uncle

[wileetundra]

Originally Posted by redhawks1

ok wilee i give. how can i post that i figured out how the ashtray works and your making Uranium PU-36 Explosive Space Modulators for the truck .
uncle

LOL

Actually, I should have patented my mod as the "Illudium PU-36" which was the revised model name for the space modulator. Somehow I don't think it would have been read or used by as many people though, so I will stick with the simpler "NAV speed pulse generator" term for now.

[THUNDERA]

The simplest and most elegant solution yet. Cheap, easy, and effective, I knew there was an easy way to cheat the system - the toughest part, to me, is going to be getting the nav unit out.

A couple questions: First off, did you need to match an input voltage for the pulse? If so, did you have to choose capacitor and resistor values at random? Or did you sit down do the back calculations and design the circuit that way? Did the 555 timer come with a wiring diagram dictating R and C values for corresponding output voltages/signal frequencies? This makes me want to get out my electronics engineering book from school and see if I can still do this type of stuff.

Also, you may want to mention in your online report that this circuit can be built on a breadboard that will allow for little or no soldering as long as you know how the nodes on the board work.

RadioShack.com - Cables, Parts & Connectors: Component parts: Breadboards & IC sockets: 6" Modular IC Breadboard Socket

Anyways, nice work. I wish I had as much time as you to come up with all this neat stuff. Now get to work on the power rear window!!

[wileetundra]

It is very easy to get the NAV unit out. The instructions are included with the metra dash kit which you can download here. I was dreading this part of the install but it was so easy that I was super-confident when it came time to start cutting all the NAV wires in the dash.

First I measured the speed sensor input voltage from the factory wire and it seemed to fluctuate between 0-10.6 volts DC depending on the speed. I feared that the sloped voltage might be critical but then I figured I only needed to emulate the 1 km/h signal so it could probably be fixed. I tested it with fixed 9 and 12 volts DC input signals and both seemed to work although I only tested them briefly for fear of harming my NAV. The final device has a capacitor on the output line which reduces the effective voltage to 0-1 volts DC and it still works as long as the pulse timing is right, so it looks like the voltage is not as critical after all.

I did a few calculations based on some 555 timer IC info which I found on the web. The IC did come with a small sheet but it was only for astable mode and we wanted monostable. Once I knew that the R and C values were close I just purchased potentiometers so I could trim them to exact values as needed. As luck would have it the max settings were right on the money and worked out without tuning, at least on my vehicle.

The breadboard isn't a bad idea but it is a little big and I believe that a mobile component should be soldered, especially if you bury it in your dash. You don't want to hit a hard pothole one day and lock your NAV functions back up...


I am really torn on which mod to complete next. I have the ACME parts and plans ready for several projects including the blind-spot cameras, remote gas door lock, and the power rear window slider for my DC. I also have a top-secret mod which I may not actually install, but if I do then it will be visible for miles around and will help me find my truck in a crowded parking lot at night. Think high power visible green lasers... errr.... I didn't say that....

[Jer]

My vote is the power sliding rear window for the DC next.

[Afterimage]

Wile E., have you dug through the contents of the Nav DVD's files with a hex editor at all?

I extracted the contents of the Nav DVD yesterday but have only done a quick skim of the files for suspect text strings that contain function on/off switches. I was using Hex Workshop for viewing.

[RC_Av8r]

Awesome!!!!

You ARE a Suuuuper Genius!

Dave

[ag4ever]

How does this mod affect the dead reconing (sp?) feature of the nav?

If you don't have enough sats in view will it still keep the vehicle at the correct point on the maps?

I am sure it is rare to not have a bunch of sats in view, but it could happen.

[wileetundra]

Originally Posted by Afterimage

Wile E., have you dug through the contents of the Nav DVD's files with a hex editor at all?

I extracted the contents of the Nav DVD yesterday but have only done a quick skim of the files for suspect text strings that contain function on/off switches. I was using Hex Workshop for viewing.

Yes, I did experiment with this. I used Power Grep 3 which allows viewing, searching, and editing the raw file content. I found several sections of text which I tried to replace or rename. The files edited, saved, and burned fine. Then the modified firmware DVD started to load fine too but it would eventually crap out just before activating the application. I think it was a checksum error or perhaps I edited some key data improperly. I ultimately decided to anandon this since I wanted a hardware mod anyway. Even if I could modify the old firmware I would still want to upgrade to the newest version each time, and with the hardware mod then all my enhancements stay in effect.

[wileetundra]

Originally Posted by ag4ever

How does this mod affect the dead reconing (sp?) feature of the nav?

If you don't have enough sats in view will it still keep the vehicle at the correct point on the maps?

I am sure it is rare to not have a bunch of sats in view, but it could happen.

It does have a very minor impact to the NAV function but it is negligible - it just makes the maps scroll a little less smoothly when you are traveling at high speed with all the functions enabled. If you use the toggle switch option then in the event of a GPS failure you could just switch it back to factory mode and no problem. Where on earth will you be without at least 2-3 satellites in range? The only place I can think of is underground in a long tunnel, or possibly in a very steep and deep mountain valley, and in those cases you would know where you are at and you wouldn't have a lot of directional options anyway.

Read my report on my mod site for the details. The link is in my signature line.

[wileetundra]

Update 9/23/2007:
My speed pulse generator report has been updated with several changes. You can view it here and then select report # 16 - NAV Speed Pulse Generator.

The first change, by popular demand, is an option to buy one of these if you can't make your own - see the Comments section in the new report for details.

The other changes are related to a new and improved circuit design. The circuit changes should make it easier to build the device and less likely for anyone to damage it during installation. On the previous design if you shorted a wire or hooked it up wrong then the 555 Timer IC would be fried thus rendering the device useless. It is a real pain to de-solder and replace the IC so I added an IC socket that will let you unplug the IC and replace it with a new one in just a few seconds. Most people shouldn't need to replace the IC but if you do something stupid then it is at least a cheap easy fix thanks to the socket.

I also found during additional testing that the three 100K ohm potentiometers were not truly needed since they slowed down the pulse quite a bit when set to the maximum setting, plus if someone turned them all down to the minimum setting at the same time then they would burn up the IC. So the revised circuit only uses one 100K ohm potentiometer in series with a 33K ohm resistor. This provides a more practical pulse rate range that is still adjustable and it prevents the IC from being damaged when the potentiometer is turned to the minimum setting.

I also replaced the 1K ohm potentiometer with a 1K ohm resistor since this doesn't need to be adjusted and the resistor is cheaper / easier to install.

Finally, I used a smaller circuit board and project box so the device would take up a little less space.

I have been using my device for a while now and it is great to drive around with all NAV functions available all the time. No more stupid lockout feature and I can upgrade to the new firmware whenever I want to without losing the bypass.

Several people have asked if this will work with other NAV units and vehicles. Based on my research I think that it will work with many other NAV units and vehicles but obviously I only tested it on my 07 Tundra DC Limited so no guarantees. The mod is cheap enough at $15 for parts so why not build your own and try it out?

Enjoy.

[wileetundra]

Update: many of you asked me to build a NAV unlocking device for you. I originally didn't want to do this because my time is limited but I agreed to help a few people out and my inbox started filling with orders. So I made a batch of the devices and just sold the last one tonight. If you still want a device then PM me now and if I get enough orders then I will make a second batch. See my updated install report for details if you want to make your own:

2007 Toyota Tundra Installation Report by WileETundra

I am anxious for the other forum members to report their results once they get it installed. No more burning DVDs or losing functionality while in motion.