2008 Highlander Limited Nav Hardware Hack

[InOmaha]

I did the 5.1/9.1 navigation DVD for a while, but got tired of hitting I Agree everytime I got in and out of the car. So I did some research around here and the internet and just finished up modifying the Nav system with a pulse timer and a switch.

I'm compiling some of the resources I found and the parts needed in this thread. I didn't take pictures of the install but I can take pictures of the final product.

You'll need to make a speed pulse generator.

I used a small 12v relay (like this http://www.radioshack.com/product/in...odsInSession=1), a TLC 555 chip for CMOS, a 1k resistor, a 10 k resistor, a couple of unneeded potentiometers so I could play with the circuit, and a 47 uf capacitor.

This site shows how the astable oscillator is put together on a breadboard. http://www.doctronics.co.uk/555.htm#pb_02

For me R1=1k, R2=10k, C1 = 47uf to get a frequency of ~1.45Hz and a duty cycle of 50%. I don't know what speed that corresponds to in the car, but it's changable by switching capacitors if need be. I did away with the 47uf decoupling capacitor and the 10nf capacitor from pin 5 to ground. The resistor and LED off of connector 3 of the 555 are there for testing the output. Not needed at the end but I did the same with a 10k resistor and an LED and it flashed pretty. Don't run the circuit without resistance on the output (3) or you'll probably fry the 555 if you don't have a fuse.

I added the relay with it set failed closed ie with no power to the circuit the signal from the Highlander VSS connected to the Nav input wire. Sending power to the circuit opened the relay and connected my 555 output to the Nav input wire.

I added a 0.315 mA fast acting fuse on the power line to protect everything because it's cheap.

I used an 8 pin retention contact for the chip and a 14 pin retention contact for the relay so I could easily replace them if they failed for some reason.

Soldered it all together on one of these halves.
http://www.radioshack.com/product/in...ductId=2104052

If you want to see the circuit in motion you can play with it here.

http://www.falstad.com/circuit/

Under file import cut and paste below into the box.

$ 1 0.0020 0.625470095193633 64 7.0 50
w 352 288 320 288 0
r 320 288 320 352 0 10000.0
w 320 352 352 352 0
w 320 352 320 384 0
w 320 384 352 384 0
r 320 288 320 224 0 1000.0
w 320 224 416 224 0
165 352 256 368 256 2 0.0
w 416 224 480 224 0
w 480 224 480 288 0
w 192 224 224 224 1
c 320 448 320 384 0 4.7E-5 -6.973199547103663
s 224 224 272 224 0 0 false
w 320 224 272 224 2
w 272 224 272 64 1
w 272 64 768 64 0
w 768 160 656 160 1
w 480 320 512 320 0
w 768 64 768 160 0
w 544 112 592 112 0
w 320 448 128 448 0
w 512 320 512 144 2
178 656 128 592 128 0 1 0.2 0.034285714285714274 0.05 1000000.0 0.02 350.0
w 656 128 880 128 0
w 880 128 880 448 1
w 592 144 592 192 0
w 560 192 560 160 0
162 752 448 656 448 1 2.1024259 1.0 0.0 0.0
174 592 144 528 144 0 1.0 0.5 Resistance
w 512 144 528 144 0
w 560 192 592 192 0
w 656 176 656 384 0
w 656 384 496 384 0
w 496 384 496 448 0
w 496 448 320 448 0
174 880 448 752 448 0 500.0 0.5 Resistance
w 816 464 816 496 0
w 816 496 752 496 0
w 752 496 752 448 0
g 624 448 624 480 0
R 192 224 144 224 0 0 40.0 12.0 0.0 0.0 0.5
g 128 448 128 480 0
R 544 112 496 112 0 5 10.0 12.0 0.0 0.0 0.5
w 656 448 624 448 2

I mimicked the Nav system in this model with a potentiometer and an LED. They don't exist in my final circuitry.

Here's how someone else did it.

http://www.toyota-4runner.org/5th-ge...-part-1-a.html

I only hook into the speed wire on mine and pull the 12 V power from somewhere else. Minimal NAV wiring that way.


Next hack into the car.

Here is the best visual guide I could find for removing the Navigation system. I used a couple of wooden shims and a putty knife. Start from inside the glovebox so if you mess up some it will be hidden.

http://www.autodvdgps.com/blog/?p=1545

After removing the nav unit you need to cut the VSS wire. It is the brown wire located in pin 3 of the gray connecter near the center of the Nav Unit. Looks just like K6 at the top of this thread. Protect your shifter nob with something.

http://www.tundrasolutions.com/forum...r-2007-tundra/

I cut the speed sensor wire and crimped a male/female blade connector to the wires so they could be put back together easily.

I ran speed sensor, power, and ground wires from my timer placed in center console by drilling a small hole in console, pulling off the trim covering the transmittion linkage, and routing the wires. It's easy to get the center trim off once you've taken out the NAV. Use zip ties and tape to keep wires from rattling. I used an old PC power connector on the end of the wires so it would be easy to plug in my speed pulse generator or take it out to work on it. Run the speed sensor wires up to the back of the NAV and plug them into the appropriate male/female connectors at the NAV unit and tape everything down tight. Put the Nav unit back in and the vent on top if you want it out of the way.

At this point you can touch the speed sensor wires together at your console and the system acts as designed and seperate them to temporarily override the lockout. I made a second PC connector with a simple on/off switch on it that I could use in an emergency if the pulse generator goes goofy on me.

My PC connecters have 4 wires
1 red for power
1 black for ground
(these to are common in applications I deal with so I used them)
1 white for from the VSS
1 blue for to the Nav
(these two colors I had laying around)

I put the circuit in a small project enclosure box in the console.
http://www.radioshack.com/product/in...ductId=2062279

Power to the system comes from the 12V power attachment on the dash next to my seat heater dials. I tapped into that and ran power to the power input lead of this switch.

http://www.radioshack.com/product/in...ductId=3118987

Then connected the power ouput lead to my circuit. The ground from the circuit goes on the top spade of the switch and then grounds to the car. This completes the circuit for the speed pulse generator and the switch LED. I've estimated about 35-40mA going around in the speed pulse generator loop, but as stated above, I put in a fuse to make sure I don't fry anything. Cheap insurance.

The switch was a little snug. It's located on the dash in between my Aux port and the seat heater dials. I took a 3/4" spade bit to drill the hole, then I had to flatten out the round nut in a couple of places and screw it in from the front (since I couldn't turn the nut). I used fingers and a needle nose pliers on the connecters to get enough grip and turn it tight while leaving the red LED on top. It looks like it belongs there.

Now when I flip the switch on, the LED on the switch lights up, my pulse generator starts pulsing, my relay switches the output of the circuit to the NAV computer, and the NAV setup comes alive. Shut off power and the relay closes, the circuit de-energizes, and the NAV works like normal.

[luck123]

You lost me after "you need to make a speed pulse generator".

Seriously though, this is pretty impressive.

Oh, and let me be the first to you to Toyota Nation!

Great group of folks here who provide great advice and share experiences/info, and great moderators that are always willing to help.

Cheers.

[InOmaha]

Thanks,

I followed most of the directions found around the internet. I need to measure the current draw of the system in normal operation and make sure my output is about the same.

I blew 2 fuses and found my inlet current draw is around 450mA. Much higher than I expected. My guess is the Relay I used isn't 350ohm resistance so the draw is through the coil on it. Pops my 315mA fuses. I'll up them to 500mA and see if it stays running or add a resistor in that part of the circuit.

I don't want to send too much current to the NAV.

This is the extent of all of the accumulated knowledge I have about electronic circuits.

Right now I can jumper the speed sensor wire and get the setup menu for ~30 seconds at a time.

[areamike]

Originally Posted by luck123

You lost me after "you need to make a speed pulse generator".

Seriously though, this is pretty impressive.

Oh, and let me be the first to you to Toyota Nation!

Great group of folks here who provide great advice and share experiences/info, and great moderators that are always willing to help.

Cheers.

I was going to say the same darn thing.

Very impressive write up. Me guesses he has some sort of electrician background. I can barely change a light bulb, so this hack is out for me. Thanks for sharing though!

I would just like a "simple" way to use the Nav system while driving. What would be cool is if there is a passenger in the passenger seat, the Nav System would work while driving. That would be good enough for me.

[InOmaha]

Originally Posted by areamike

I was going to say the same darn thing.

Very impressive write up. Me guesses he has some sort of electrician background. I can barely change a light bulb, so this hack is out for me. Thanks for sharing though!

I would just like a "simple" way to use the Nav system while driving. What would be cool is if there is a passenger in the passenger seat, the Nav System would work while driving. That would be good enough for me.

They should have put an override switch on the passenger side seat. Like their air bag and seat belt sensor system that detects a passenger. Then your override would be about 30-50 lbs of weight on the front seat.

I'm a mechanical engineer who likes to tinker. I've been taking it slow with this electronics stuff. There are third party versions of this that are much more plug and play and will let you turn the NAV on while driving, but they seemed expensive at $250-$300 and you still needed to take apart the dash. It would have been much faster and easier to buy one of them and then follow the section on taking apart the dash above. I spent about $20 in parts.

http://www.coastaletech.com/APPLICAT...IDE%20REV2.htm
http://www.prestigioussociety.com/

I'm still having a little problem with the fuses so I'm using the setup in jumpered mode while I play around with the circuitry in my box. I use a switch in the console to turn on the NAV setup and after 30 seconds I switch it back on and off to get another 30 seconds. Not the best solution. I could always unfuse my circuit and see what happens, but I think I'll take it slower and figure out what's going on.

I'll take some pictures of the final install and post them after I figure out how.

[areamike]

Your definition of "tinker" and mine must be two totally different things!

[InOmaha]

I went an bought another chip for $1.70 put it in and the circuit draws 43mA. The chip resistance was much much higher. I must have shorted the other out testing it. That's the reason for using retention contacts. Soldering those in permenantly while allowing removal and replacement of the "moving parts".

I did some testing on the way home. The speed pulse wire didn't have current going through it. It was at 12V parked and went down to 6V moving. My meter moved a little but the pulses were too fast for it to pick up. You could see it vary more as you slowed down and got closer to the 12V signal.

The circuit I built should output ~12V at a pulse rate tricking the car into thinking it's going ~2.5-3mph.

I'll get into the service screen tonight with the lights on/off method and verify the VSS speed signal with the circuit on. I did it once before, but I need to find the service screen sequence again.