Anyone interested in how to bypass the factory navigation speed lock?

Ships in 1-2 weeks

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Edit: I will use this post to update any news and FAQ of the bypass. Original Post has been moved to Post # 6
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The speedlock override is available in Priuschat Shop PriusChat Shop : Toyota Prius Navigation Speed Lock Override [Prius Nav Override] - $90.00
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Click here for installation instruction for 2010-2012 Prius hatchback
Click here for installation instruction for 2012 Prius v posted by anewhouse and russcarver - First Navigation Speed Lock Override (from the PC shop) in a Prius v: SUCCESS! | PriusChat
Click here for high resolution pictures of what the different versions of the bypass look like
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Current Stock Level - Updated 05/13/13
This will be my last batch. After current stock sells out, I will not make anymore.
V1 -------- 17 shipping in 1-2 weeks
V1V ------ 12 shipping in 1-2 weeks If you're interested in ordering the V1V, Read This
V3 -------- 0 in stock. estimated shipping in 6-10 weeks.
V3V ------ Not available. Please do not order. If you do, your order well have to be either changed to other versions or be refunded. (11/5/2012)
All orders will ship 1-2 weeks after your order date.
Updated 05-13-2013

News

V1 orders placed on or before 8/10/2012 used 78k ohms for R2. What this means is that the simulated speed is between 2-4km/h. You can verify this by going into the service menu and check the vehicle speed.
V1 orders placed on or after 8/11/2012 used 1m ohms for R2. What this means is that the simulated speed is between 0-1km/h. You can verify this by going into the service menu and check the vehicle speed.

FAQ

Which one do I order? Updated 2-10-13
2004-2009 supported but not recommended as the override will not not auto click the OK button when viewing the map. I recommend purchasing the Costaltech’s lockpick. It is designed for GenII and it’s plug and play. However, V1 or V3 will work with Gen II’s speed signal. The switch panel probably won’t fit the Gen II’s blank panel.

2010-2011 III, IV, V, Three, Four, Five with stock JBL navigation system - V1 or V3
2012 Prius Two, Three, Four, Five, Plugin Prius Base model with 6.1" Display Audio - V1 or V3

2012 Prius Four Deluxe Solar Roof Package 7” Touch Screen - V1V
2012 Prius Five Advanced Technology Package 7” Touch Screen - V1V
2012 Plugin Prius Advanced 7” Touch Screen - V1V

2012 Prius c Three and Four with 6.1” Display Audio - V1 or V3

2012 Prius v Two, Three, Five with 6.1” Display Audio - V1 or V3
2012 Prius v Five With Advanced Technology Package 7" Touch Screen - V1V

If you still don’t know, put a DVD movie in your CD slot. If it can play it then V1V. If not, V1 or V3.

If your vehicle requires the V1V but you're not interested in enabling DVD playback while in motion, you don't have to hook up the red and pink wires to the parking brake wire, just tape them off. When you decide to enable the DVD playback while in motion, just hook up the red and pink wires to the parking brake wire behind the head unit. Added 6-3-12

If you're interested in ordering the V1V, Read This

I don’t see my Prius listed
Contact me. I might have missed it.

What’s the difference between V1 and V3?
V1 means that the switch is a 2 position On-Off switch. The On position latches the override relay and circuit so the override is active. The off position is just that, off.
V3 means that the switch is a 3 position switch much like the power window switch except the first position is latched and it latches the override relay and circuit so the override is active. The off position is just that, off. The 3rd position is momentary exactly like the power window switch. After you press and release it, it activates a timer relay. If you activate the timer relay and decided that you want to dis-engage the override, turn the bypass on then off.

What happened to V2?
V2 was designed but was scrapped and replaced by V3. When V2's override is in the timed mode, the timer can not be manually disengaged. You'll have to wait until the timer to self-disengage. V3 adds the ability to manually disengage the timer.

How much time is the Timed? Updated 5-22-12
The default setting on the 528T is about 30 seconds. The V3 and V3V will ship with the timer set at the longest setting, 60 seconds.

What’s the difference between V# and V#V?
The V at the end signifies Video. V#V does what V# do but also switches the parking brake signal so the nav unit will also display the DVD video at any speed. It is intended for hard drive based navigation with 7” screen. Since the V#V are late add-ons and in order to keep the price within my previous quote, the extension harness for the switch and the VSS and parking wires are not detachable like the V#. Also there’s no bypass loop included like the V#.

Is there an always on version? Added 9-18-2012
No. If you prefer an always on version, just turn on the bypass and tuck the switch behind the dash panel. I don't recommend doing this as I have no idea what would happen in the long run.

My LED doesn't work (V3 and V3V only) Added 6-3-12
The blue/green LED light is strictly for visual confirmation that the bypass is active. The original design was that the blue LED was for the ON mode for all the 4 types of override while the green LED was for the timed mode for the V3 and the V3V. After much of testing of the V3 and V3V, the blue LED would burn out for unknown reason after some use. The bypass continues to work but without the blue LED lighting up. However, the green LED continues to work in the timed mode. The V1 and V1V does not have this issue. I've tried doubling the resistor value (940 ohms) recommended for 12V (470 ohms) but the LED still burns out. After more testing, I've switch the LEDs around and use the green LED for the ON mode and blue LED for the Timed mode. This seems to work without burning out the blue LEDs. Time will tell. New batch of V3 and V3v shipped after memorial day 2012 will have the new design with Green LED for ON mode and blue LED for Timed mode. If the LEDs continues to fail after the new design, I will have no choice but to disconnect the LED for ON mode and only use the green LED for the timed mode. If your V3 or V3V has a burned out blue LED, contact me for resolution.
V1 and V1V only Updated 01-04-13
Most common reason - The LED flashes once quickly then stays off when the power wires has been wired up backwards. The black wire on the bypass (ground) has been connected to the black wire (+12V) on the cigarette lighter harness. If this happens, turn off immediately or else you'll fry the 555 timer. Even with a fried 555 timer, the bypass will still work but it may only work for a minute.
The LED on the switch does not work. I was sent the wrong switch and wasn't able to work it out with the seller. I have built a blue LED to take its place.

What’s a bypass loop? Updated 9-18-2012
A bypass loop comes with every V# unit. It is the small looped molex plug that came inside the installation parts bag. It is intended for trouble shooting the override after the installation. Once VSS harness has been wired up, you can plug the bypass loop into the VSS harness without taking the radio out of the dash to check if the weird symptoms still exist without the override in place.

Can I order V#V even though the list only show V#?
You can order the V#V for your Prius that does not require parking brake switching. You just don’t wire it up.

What speed does the override simulate? Updated 4-10
V1 @ 2-4 km/h. V1V, V3, V3V @ 0-1km/h. Less than 8km/h enables all the grayed out buttons.

What's the difference between the PC shop's override and the Prestigious Society's and the Beatsonic's override? Added 4-10
PC Shop's override starts at $80 for basic on-off switching. The connection requires the installer to splice the Vehicle Speed Sense wire and T-Tap the power wire. This allows the override to be installed into recently built Toyotas and Lexuses. It is not limited only to the Prius lineups. The switch is made fit Gen III Prius's blank switch panel. Other models may require minor shaving. The override started out as a DIY how to with instructions. Forum users weren't able to build them and requested that I build it for them. In order to comply with the forum policy, I offered the override through Priuschat Shop.
You can learn more about Prestigious Society's override herePrestigious Society » Navigation and Video Enhancement Module
You can learn more about Beatsonic's override here Toyota/Lexus - NAV/DVD BYPASS

I don’t see the installation instruction for my Prius. Updated 4-10
The override was originally intended for 2010 and 2011 Prius only. It was later expanded to cover 2012. The v and the c were a last minute add on. The only installation instruction available I have is for 2010 to 2012 Prius Hatchback.
For 2012 Prius v Please refer to anewhouse's instruction at First Navigation Speed Lock Override (from the PC shop) in a Prius v: SUCCESS! | PriusChat
There is no instructions for the 2012 Prius c at this moment. However, you can still order one and create your own installation instruction to assist other c owners. The wire color is the same as the Prius v. The switch fits the blanks next to the EV and ECO switch in center console. Updated 5-22-12
I used the override and I hit somebody. Who can I sue?
If you have the Advanced Technology Package, you can sue Toyota for the Pre-Collision System failing to operate.
If you don’t have ATP, no one really. The override is intended for your passenger, not the driver. I leave it up to your good judgment on how to use your own vehicle. I could be a donkey and design the override to only work when there’s a passenger sitting in the front passenger seat. But that would defeat the purpose of a cheap and inexpensive override and its true intended purpose.

If you decide to order, please PM me your model, trim and package of your Prius and which override you intend to order. If you order the wrong one, it’ll delay the shipment.

Any questions please contact me before ordering. I will add more FAQs as time goes by. Thanks very much.

3-30 Edit
Added revised installation instructions for 2010-2012 Prius Hatchback
Added hi res picture of the bypass in zip file. From the top, V1, V1V, V3, V3V.
5-22 Updated FAQ
6-3 Updated FAQ
9-2 Copied FAQ to Original Post. FAQ on post 69 will not be updated from now on. It will have the the installation instruction PDF and the high res pictures of all the bypasses.
10-15-12 Added wiring info

4 sure :rockon: There are five avatars waiting for an update on this topic and one XMAN LIVE waiting on the edge of his seat.
seems to be three more spectators in awe.

I am very interested. The speed lock is my biggest peeve with the Prius.

I'm always interested in "hidden" features. What model prius are we working on here. Is the new Prius (Wagon) that I see you own. Does the bypass have to be applied every time you start the vehicle? Enough teasing show us PLEAAAASSSEEEE!

I now see we are in a Gen III forum so I know what we are working with.

His is an uppercase V, not a lower case v, so it is not the wagon. (Why Toyota thought this was a good naming idea escapes me)

I built one just for this tutorial. It's not quite done yet. It has a switch to turn it on and off so don't worry about it constantly being on. It's not good for the nav with the speed lock constantly bypassed. Bypass it only when you need it. Anyways keep voting to show your interest or the lack of.
As you can see from my profile, I have a 2010 Gen III Prius V with ATP. It came with nav. I can't replace it b/c of the parking assist.
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Edit: Moving Original Post here
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I have sold out of V1. V1V is low stock. V3 and V3V are in stock. V1 should be in stock by the end of the month.
The speedlock override is available in Priuschat Shop PriusChat Shop : Toyota Prius Navigation Speed Lock Override [Prius Nav Override] - $80.00 FAQ and installation instructions at post #69 Anyone interested in how to bypass the factory navigation speed lock? | Page 4 | PriusChat

Background

Navigation speed lock activates when the vehicle's speed exceeds 5mph. It locks out almost every function so you can't manipulate majority of the settings. I've been running the speed lock bypass that I built for almost a year with no problems so I thought I'd show you guys how to do it. This is a basic step by step on how to bypass the navigation speed lock on Gen III Prius with factory navigation system. I'll also try to explain the basic concepts of it. You do need some soldering skills.

Warnings

1 - Operating the unlocked navi is almost like texting while driving. It takes your eyes off the road. I will not responsible for your actions as a result of this modifications.
2 - I have broken down each step as easy as I can. If you get lost following my direction, don't blame me. If you build it and failed to function as described, don't blame me.
3 - Because this is a DIY project, there's no telling weather it'll work for your navigation system or not. I will not be responsible for any damages to your navigation system or your vehicle caused by this modification.

Basic concept

The factory nav system has a speed sense wire coming from the vehicle. It uses this signal to determine vehicle speed and not the GPS signal. (If it was GPS based, this bypass would not be possible) It locks out a lot of functions when the speed exceeds 5mph. If you think you can use voice activation, you better know exactly how it works because if you ask for help on the voice commands, it will tell you to stop the vehicle. This pretty much defeats the purpose of voice control.
[FONT=&quot]In order to bypass the speed lock, the nav system must receive a speed signal of less than 5 mph. The speed signal for most Toyotas is 4 pulse per tire rotation as shown in this picture. This includes the Gen III Prius.[/FONT]

Source Navigation Input Override (Speed Sensor Bypass) | PriusChat Thanks to rachaelseven for posting it. I believe Gen II also uses this signal. If it does, this will also work on Gen II. You just have to locate the speed sense wire behind the display. [FONT=&quot]Check out Prius Speed Wire for Gen II VSS wire location.[/FONT]
In order to reactivate nav, phone, audio and settings control, we need to build a circuit that simulate a speed below the speed lock threshold and feed that signal to the radio regardless of what the vehicle speed is. We can do this by building an astable 555 timer circuit and time it at less than 4 cycles per second.
[FONT=&quot]According to my calculations 215-45-17's RPM is 819 rev/mile 1mph = 819RPM/60minutes/60seconds= .2275hz. There are 4 pulse per tire rotation so .2275hz*4= 0.91hz per mph. [/FONT]According to brosnan at Navigation Input Override (Speed Sensor Bypass) | PriusChat

A lot of the information can be found in this thread Navigation Input Override (Speed Sensor Bypass) | PriusChat

Shortcuts

There are none that I know of. Do not cut the speed signal wire and leave circuit open. You will get a hybrid system warning on the dash display. I've spent a few days analyzing the speed signal trying to learn as much as I could. The speed signal alternates between positive and negative 14v at less than 1mph. As speed increases, the pulse increases and the voltage decreases because of the faster alternating frequency. Knowing that it alternates between positive and negative, I analyzed the signal when parked. Just as I suspected, the speed signal rests at either positive 14v or negative 14v at complete standstill. Don't get your hopes up thinking that you can just feed a positive or a ground into the speed signal wire. It will only work for about 70 seconds. I timed it. After that it goes to dead reckoning and locks you out because it uses GPS signal to determine vehicle speed. Reconnecting the speed signal continues the speed lock out for additional minute or so. I didn't time it. The gyro sensor continues to work even at artificial 0mph. I don't know if it gets heading from the GPS signal or an actual compass.

Parts You'll Need

The parts you need are
555 timer radio shack part# 276-1723 RadioShack® LM555 Precision Timer (8-Pin DIP) - RadioShack.com
8 pin IC socket RSP# 276-1995 8-Pin Retention Contact - RadioShack.com (Optional for easy soldering)
4.7uf capacitor RSP# 272-1024 4.7 uF Electrolytic Capacitor - RadioShack.com
.01uf poly-film capacitor RSP# 272-1065 0.01µF 50V 10% PC-Mount Capacitor - RadioShack.com
1k-ohm micro size potentiometer RSP# 271-0280 1K-Ohm Horizontal-Style Trimmer - RadioShack.com Pots are used for adjusting frequency. You can use 1k ohm resistor for R1
1000k-ohm micro size potentiometer sP# 271-0284 100K-Ohm Horizontal-Style Trimmer - RadioShack.com Pots are used for adjusting frequency. You can use 39k ohm resistor or higher all the way up to 2M for R2.
3/32" heat shrink
3/16" heat shrink
electrical tape (3M Super 33+ works best)
black zip ties
6' of 18awg red, black, blue, violet, violet/black stripe wires. I chose these colors because they are readily available from any stereo shops. You can use whatever color you want. To keep it simple, you gotta have 5 different color wires.
ON-ON SPDT rocker switch. similar to GC switch 35-640 35-640 GC Standard Rocker is the easiest way to feed the bypass signal to the headunit.
fuse holder
2x pink or blue T-Taps
4x pink or blue T-Tap terminals
5x pink or blue shielded 1/4" speaker terminals

Tools you'll need

crimper similar to Channellock 909
wire stripper similar to Channellock 957
heat gun
solderingiron with fine tip and solder
12v battery
LED lights for testing (see the signal visually)
multimeter for testing
oscilloscope for testing (optional)

Basic concept of 555 timer

Before we begin, take a look at Astable 555 Square Wave Calculator for calculating the 555 timer. That site shows the most accurate depiction of an actual 555 timer and its terminals and where each terminal connects.
According to the calculator, C = 4.7uf (0.0000047f), R1 = 500ohms +-10%, R2 = 78kohms will yield 50.16 duty cycle (the signal is 50.16% on, 49.84% off) at 1.961hz You can adjust R1 for a closer to 50% duty cycle however, the lower the resistance the hotter the resistor becomes. .5k to 1k is ideal.
and R2 for faster or slower frequency. It must be 39k or higher. Lower than 39k will result in faster frequency and the lockout won't get overridden.
Also look at Convert microfarad to farad [SI standard] - Conversion of Measurement Units for converting microfarad to farad.

The build

Instead of building a circuit on a breadboard or an actual circuit board, it'll be easier and faster to build it as a harness.




Strip a section of the wire and leave about 3 inches






Cross the wire and twist it




cut the wire and leave about 3 inches. The red wire should look like a cross with 3 inches on 3 ends and a long wire at the bottom end.


Do the same with the black wire.
Cut 2x 6" blue wires strip them in the middle, twist them together
Cut 1x 6" black wire and 1x red wire, strip them in the middle and twist them together.


bend the wires as shown above and solder the wires.
The red wire should have 2 short ends together and a short and a long end together.
The black wire should have 1 short end by itself and 2 short ends and a long end together.
The blue wire should have 2 short ends on each side.
The red and black should have one of each on each end. After soldering black and red wire, cut the black wire off at the solder joint. You should have 1 red wire on 1 end and a red and black wire on the other end. See picture below.


Once you've done soldering, cut 4x 3/16" heat shrink at 3/4" length


heat shrink the solder joints. At this time, cut a 6" black wire by itself


Cut all the wires at the same length to eachother and strip the ends for soldering to the 555 timer socket


Pre solder all the ends for easy soldering to the socket pins.


Once you've done soldering the ends , cut 8x 3/32" heat shrink at 3/4" length


slip the heat shrink onto each of the ends.


Easy to follow schematic


The 555 timer has a small circle on it. placing the 555 timer so that the circle is on the top. Looking at the 555 timer with the circle at the top, the top left pin is pin #1. refer to schematic on Astable 555 Square Wave Calculator


The 555 timer socket also has an indent to denote which side is the top.


Now we know which is pin #1, we can start soldering. Pin #1 is the ground wire. Solder the black wire with 1 short wire on the top to Pin #1.


Solder the blue wire with 2 ends to pin #2. It doesn't matter which end you solder.


Pin #3 is the output. You should solder a long blue wire to pin #3. This pin will be connected to a switch.


Solder the red wire with 2 short ends to pin #4. Doesn't matter which one you solder.


We're done with 1 side, You can put a piece of paper between the pins so it's easier to see. Notice the pin layout on the 555 timer. In case you didn't look at the schematic, the pin layout is as followed
1 8
2 7
3 6
4 5
For pin #5 you need to solder the short 6" black wire.


For pin #6, you need to solder the other blue wire from pin #2 The blue wire with 2 ends at each end goes to pin #2 and #6.


For pin #7, you need to solder the solo red wire on the black and red wires.


For pin #8, solder the other red wire from pin #4








Slide the 3/32" heat shrink tubing to cover all the soldered pins and heat shrink them.


Strip the black wires on pin #5 and one of the black wires from the ground wire on pin# 1.

Solder the .01uf capacitor to those 2 wires.


Strip the last of the ground wire from pin #1and one of the blue wire from pin#2 & #6 and solder the 4.7uf capacitor to those 2 wires.


R1 is the 1k ohm potentiometer and R2 is the 100k ohm potentiometer.


The single pin by itself is the one you have to use. You only need to use one of the 2 side by side pins.


You can cut one off. It doesn't matter which one to cut. You can still adjust the resistance on the pot.


Red wires are for R1 (0-1000 ohms) Black/blue wires are for R2 (0-100k ohms)


Once the 555 timer circuit is done, it should look something like above


The oscilloscope shows the sine wave of 3.93hz. This is the perfect signal for the nav unit to enable all the functions.


Now the circuit is built, we need to add more wires to make the installation easier. Since the speed sense wire behind the radio is violet, I chose the universal right rear speaker wire colors. Violet will be connected to the navigation unit, Violet/black stripe will connect to the harness side that goes to the car. Blue will be the signal output.


Strip the wires so you can crimp the shielded 1/4" speaker terminals to them.




The ON-ON switch is single pole double throw. The center terminal is the common terminal. This terminal goes to the navigation unit's speed sense wire. The end terminals are the switching terminal. It doesn't matter which terminal you connect the blue wire and the violet/black stripe wire to. The center terminal is constantly connected to either top or bottom terminal pending on the position of the switch.


You can add a fuse holder for the 555 timer's power input as a precaution. I used a T-Tap fuse holder because I had some laying around. They are easy to integrate

















You can tape up the all the wires together to make it look neat. This is what the end product should look like.
Red and black wires are for power and ground. The switch is for activating the speed lock bypass. The violet and violet/black stripe wires will connect behind the navigation unit.

Testing

Connect the power and ground to a 12V source such as a power tool battery. Connect the violet/black stripe wire to same 12V+. Connect the LED's + to the violet wire and ground the LED's - terminal. The LED should light up simulating the vehicle's high speed pulse. Flip the switch and the bypass circuit's output will get switched to the LEDs and pulse.

Trouble Shooting

If your timer does not flash the LEDs like the video, reverse the 4.7uf capacitor.

Installation

This circuit is intended to be installed behind the cigarette lighter under the bridge. There you will find the power needed for the circuit from the cigarette lighter. The black wire is ACC-ON, The White/Black stripe wire is the ground. DO NOT USE THE BLACK WIRE ON THE CIGARETTE LIGHTER FOR GROUND!! IT IS ACCESSORY +12 VOLT.
For III, Three owners, you can install the switch at the blank space intended for the Heated Seats Switch.
For IV, Four owners, you can install the switch at the blank space intended for the IPA switch.
For V, Five owners, you can install the switch at the blank space next to the headlight washer switch.
For radio removal please refer to this clip


Once you got the radio out of the dash, look at the back of the radio and locate the gray plug

Source Navigation Input Override (Speed Sensor Bypass) | PriusChat Thanks to hawkmoon77 for posting it. BTW Do not follow his direction #3 in that post. It's proven not to work.

Locate the violet wire in pin 3 of the gray plug. You may have to peel back the electrical tape and wire protector to access it.
Once you locate the violet wire, you must cut it in half. Leave enough room so you can re-connect it back in the future.
connect the violet wire from the bypass circuit to the violet wire on the stereo side.
Connect the violet/black stripe wire from the bypass circuit to the violet wire coming from the car's harness.
slide the nav unit back into the cavity. Reconnect all the plugs before powering the Prius. You can take it out for a quick test drive to make sure it works before reassemble the dash.

Final operation

Flip the switch to reactivate all the functions of the navigation unit while cruising down the road. Remember to turn it off once you're done.

Known side effects

There are no known side effects if you don't use the navigation/map function.

If you use the navigation/map function, this modification will cause the GPS display incorrect position. It will stop at the position where you first activate the speed lock bypass. Because the speed lock bypass sends an extreme slow vehicle speed signal to the navigation unit, the nav unit is going to react to the speed it receives. This will cause the GPS position to either move slowly or completely stop. The GPS position will recover to its accurate position within a few seconds after turning off the speed lock bypass.

This is the inherent nature of all GPS speed lock bypass. Even the Prestigious Society's nav lock bypass does it

Prestigious Society Navigation and Video Enhancement Module - YouTube

Credits and Thanks

Navigation Input Override (Speed Sensor Bypass) | PriusChat has alot of information hawkmoon77 rachaelseven jayvee are the major contributors.

WOW! It's possible to bypass this big dumb thing that won't let us look for food? How have we evolved this far such that we can't source good grazing if moving more than 5(?)mph? How many times can I vote?

I gave up on getting navigation with cars after being burdoned by having to purchase update DVD's every year or so. Found my $200 Garmin Nuvi does everything I need it to, and does not have the stupid lockout features (like what came on our old Pontiac, and we currently have on our Volt)... On the Volt it is worse than this because if you are going any faster than 0mph (granted a 5mph limit does not make the Prii stuff anymore useful I suppose) you cannot do anything at all whether it is with the Nav, enter phone numbers, etc. I think these interlocks are stupid anyway since obviously it doesn't stop any of us from bypassing them. Certaintly a good write up, and thank you for taking the time and effort to post it.

Original post has been updated. I hope this will help you guys on your quest to bypass the speed lock. If you have any questions, I'll do my best to answer them. Thanks and ENJOY!!!

Wow--that's the most detailed DIY I've ever seen. Nice job.

Nicely done, +1 and then some.

I will be duplicating your efforts, I can do a quick PC board layout and I have access to a prototype PCB maker, this is going to be a nice project.
Your write up was perfect!
Good Job, thanks for the idea!!

Cpro,

Props for using a 40 year old and still appropriate IC, the 555.

thanks! This will be a mod of mine in the future!! Do you know if this will work on a 2010 Lexus Is250? I did the switch on that car and it works, but it only lasts for less then a minute.

I will also be doing this on my prius if I can get it to work!

Normally I bypass it long enough for me to do things that I needed to do. I have a better switching system than the one posted here. The bypass in this post is only on-off. My system is On-Off-1min timed. It's normally in the off position. If I need to enter an address, I push the 1 min timer, 1 minute is enough for me to enter an address. After the 1 minute, the bypass deactivates and automatically goes back to normal. This setup will work for as long as the switch is turned on. I added the 1 minute timer for in case I forgot to turn off the bypass. It could work for IS250 if it uses the same speed signal as the Prius.
If you simply add a switch to the speed sense wire, it'll work for less than a minute then it goes back to locked. Switching the switch off and on again will not reactivate the bypass. It'll lock out for another minute I think. This is why you need this circuit to bypass the speed lock correctly.
Most people don't know how to make PCB or can't read circuit schematics and symbols. This is why I'm making this circuit as a harness. It's easier to make.
I'll make another schematic with labels for easy reading.

cproaudio,

What would you estimate the cost of the materials required to make this harness is? I have most of the tools already and access to shop test equipment at work. For a novice how would you rate the difficulty from 1-10? I showed this thread to the avionics electrical shop supervisor and he was impressed and wants me to try and build one. Would building it on a circuit board be easier or harder? Do you plan on building any more if so what would you change if anything. TIA!

I would say that it is harder if you have to build it from scratch without a specially designed PCB like using one of these Dual Mini Board with 213 Holes - RadioShack.com. I would give it a 6 or 7 because soldering on a tight PCB is a bitch. If you build it like a harness like my instruction, I'd give it a 3. The hardest part is soldering the closely positioned pins on the 555 timer.
The total cost should not be more than $30 if you buy the parts from radio shack. If you buy all the parts from specialty electronics store, it should be around $15-20.
I still have the one I built for this instruction that's sitting in my room. I'm not sure that's the protocol for making and selling something like this on PC. I know PC has a strict policy for selling. I don't mind building this circuit for those that can't build it for a fee but I don't wanna do it if it gets me banned.

I made a couple videos with the speed lock bypass.

As much as I'd like this, I use the GPS so infrequently while moving that I don't think I want to go through the hassle of building that, getting the tools, and taking the NAV out of the dash. That said, a very detailed DIY how-to!

The speed lock not only locks out the navigation functions. It locks out the audio and the phone functions as well. The number pad on the phone grays out. Some of the folder and track selection on the USB grays out too. Some of the voice commands are locked out too.