[ KB ] How to Install a Navigation System Defeat Switch

You're certainly right about that. They wouldn't know what caused the problem.

 

Just wanted to give you guys a thank you for putting this up. Went through the procedure yesterday, and it went off without a hitch - definately have to make sure you go for the right wire (the thinner purple wire in the middle), and it also helped to have two people when it came to the soldering, but otherwise very cool stuff.

Albeit a small one, I have taken the step to mod my prius, and it's a joy!

-m.

 

For those that are curious, I find the signalling as follows:
Voltage toggles between 0 and 13.6V.
Changes state about once per foot or so if rolling above a min speed,
both forward and reverse.
Freezes at either 0 or 13.6 if you stop.
Electrical levels are not quite consistent with a pullup resistor in the nav
unit and a switch to ground in the speed sensor (wherever that is).
Too bad, because then a switch to ground from this wire would be fine
and you wouldn't need to cut the wire - just tap into it.
Short circuit current to ground is 8.2mA when in the high state.
Current through a 150 Ohm resistor to ground is 6.8mA (high state)
Current through a 1.5K Ohm resistor to ground is 2.2mA (high state)
Maybe someone who's cut the wire can say what the current
through the switch is in each state?

I might be tempted to ground the metal body of the switch to
improve the odds in an ESD hit. Maybe even a surge suppression
diode between the purple wire and ground for extra protection.
Another method might be to use magnetic window alarm sensors
so you could open the speed sense line without much chance
for zapping it with ESD.
2004 #9

 

I was very happy to find a thread on this subject - does anyone know if a mechanic would do this since I'd hate to screw something up during the modification. Thanks!

 

I can't solder to save my life, but I strongly recommend connectors and a crimping tool. I went to Radio Shack, and in the back where all the electronic parts are kept, there's a bunch of steel drawers marked with the types of small parts in each drawer. I found a drawer labeled "Automotive Connectors", and selected 1/4" Fast-On connectors. A bag of 5 pairs cost about $2. I also bought a spool of 22 gage wire, which is about what the Prius uses, and a $6 crimping tool that has a wire cutter, wire stripper and multiple crimpers for different gage wire. This was about as idiot-proof as I could find (and needed!). Total cost out the door was around $20, and most of it is still available for future mods.

 

Glad to hear I can do it w/o soldering ... that was the part that was scaring me. I'll ask the wife what she thinks about me screwing around with our new car. Wish me luck!

 

Glad to find you all,
How can I disable the speed sensing for the Bluetooth phone system. AND am I reading this thread correctly, you can only disable the speed sensing to the Navigation system for 30 to 60 seconds at a time while driving? before the systems GPS detects somtthing is wrong and disables anyway? ALSO, I'm assuming that the thin violet wire as described under the arm rest is the same as the one behind the glove box and it's only a matter of preferance where one cuts and installs the switch??
I know, a lot of questions, I really appreciate the help. Anyone want to email me directly, I'm at [email protected]
Thanks again.

 

Don,
Have a look at this thread: http://priuschat.com/forums/viewtopic.php?...=456&highlight=

It discusses some of the options. You are right that the switch method
only defeats the lockout for a while, then a secondary lockout kicks in.
You can of course toggle the switch once in a while and maintain fairly
continuous control.

 

Does anyone know if there is a software hack for this? I assume the disk in the NAV system is a standard DVD and could be copied and modified.

 

I would also like to know if there is a software solution to this (nav defeat)and/or the Phone defeat.

 

It's really not all that hard, even for the mechanically disadvantaged...

I used a Radio Shack #275-1565 switch, which needed only a 3/8" hole. it's a push-on/push-off, and i'll upload a photo of the finished item asap.

you don't have to remove the armrest. just unlatch the cover and swing it up out of the way, then reach in and pull out the little piece of "carpet" on the bottom of the well under the armrest. that exposes the 10mm bolts. a ratchet and extension are really great here, and you can leave the bolts in the holes when you tip up the armrest/console assembly, too. those doggone philips-head screws on the front/bottom of the console were on tight!.

i soldered about two feet of light weight clear plastic speaker wire (Radio Shack or Home Depot), about 18 gauge or so, onto the switch, then threaded the wire through the hole i drilled in the console. ran the lockwasher and nut down the wire and used a small adjustable wrench to secure the switch.

while the whole process took me about 45-50 minutes (i solder well and am not mechanically challenged) 8) , it seemed like it took me half of that time to find the doggoned little purple wire and get enough of it loose to cut and strip! ukeright:

i also used small wire nuts to connect the ends of the switch wire to the purple one; it might be too tight in that little cramped space to fit a nice crimping tool! finally, i pulled the loose wire back into the space under the front cup holders and taped it down so it wouldn't flop around or rattle in the future.

all in all, the directions from the Good Doctor made this a really quick and easy install! thanks again to those who went before.......

 

I've installed the nav defeat switch and just cut the wire for the phone defeat. Everything works fine. BUT, I would still like to find out if anyone is working on a software hack??? It would be so much nicer. I have been in other cars that have mostly the same software for the nav as the Prius ie..(Hummer). and none of the other cars have to concern themselves about defeat switches. their nav system inputs work weather they are moving or not. So, if anyone knows of a software solution for these defeat switch fixes I would love to know about it.

Thanks

 

Has anyone tried this defeat switch on the older '02 prius?

Aaron

 

Didn't know '02 had nav. On '03, speed input is pin 5 on connector N2, also a purple wire.
Probably would have the same side effects as on the '04/'05.