Spare smart key?

Wait a minute! Don't have our Prius yet. We're on "The List". Are you saying that the Prius only comes with one key and you have to buy a second one? Or is it just that you bought a used Prius that only came with one key. What about valet parking? They're are some places were go that are basically valet parking only, unless you want to park blocks away, in areas that I don't care to walk in. That's why it's secured valet parking.

 

I was really excited about our Prius but when I hear some of these problems, like this or "stinky Prius', I begin to wonder. I don't mind challenges. I don't like extortion.

 

I just lost my 2007 Prius SKS key fob. At least I still have the metal key.

Sounds like my best option is to buy two 2007/2008 fobs from eBay, then have an immobilizer reset done at the same time that all 3 fobs are reprogrammed.

Does that make sense?

--tom

 

I don't know what this 2007/2008 stuff is all about. The 2004 (and maybe the 2005) used a unit that doesn't work on later model years. The newer design should work with everything, 2004-2008. There is no visible difference between the 2004 fob and later versions, so you can't really tell by looking.

All Prius fobs can be programmed to work in the keyslot. So black logo, silver logo, 2004, 2005+, doesn't make any difference for the transponder (keyslot) function.

Black logo keyfobs are required for the keyfob buttons with non-SKS/Smart cars. These are cars without the black pushbutton on the doors and trunk. In the US, these are base or package #1 models.

Silver logo keyfobs are required for the keyfob buttons and the proximity function on SKS/Smart equipped cars. In the US, these are package #2 and above models.

Once you have the proper year/color keyfob, it really gets dicey. A fresh from the parts department keyfob can be added with the dealer scantool, and perhaps with a chicken dance.

Once a keyfob has been used, the car may or may not accept its identification. Sometimes the "add key" scantool function is successful, but usually it is not. My guess is that the keyfob starts at a base code sequence, and increments that sequence each time it is used. There is some small limit on how many times that sequence can be incremented before the immobilizer can't recognize it.

Apparently a fresh immobilizer does a more extensive search of the possible sequences. So a reflashed/reset immobilizer may recognize a keyfob that failed recognition with a used immobilizer.

So what you have here is my guess at what's happening after watching the games for several years. If you use anything except a new from the dealer keyfob, then you're risking that the button/proximity functions cannot be utilized.

My preference is to have at least 2 fully functional keyfobs. If one is lost, then the other can be used with the scantool "add key" function to add a replacement. Then for keyfobs 3-5, you can use the cheapest black/silver/2004/2005+ keyfob that you can find on eBay. Unless the keyfob is truly defective, then you'll be able to use it in the keyslot. Program the new keyfobs according to ... http://priuschat.com/forums/knowled...lly-how-program-non-sks-key-fob-detailed.html in the knowledge base. The keyslot function will probably work. The button/proximity function might work, but probably not.

You can get copies of the mechanical key anywhere keys are duplicated. Just explain that an ordinary non-transponder Toyota keyblank works. It's usually a number like TR47 or similar.

If you get a keyfob from somewhere besides a dealer, let us know how it works out.

As they say in Las Vegas, Good luck!

 

Rest assured you new Prius will come with 2 key fobs.

I hope you're getting an SKS system. It's fantastic. The "key" never comes out of your pocket (or purse).

 

Thanks for the thorough explanation. I just lost the fob yesterday and decided to get on a replacement track quickly. I'm pretty sure I understand the situation.

I was considering a SKS fob from eBay, though I may just get a new one from the dealer (ouch!) to leave at home then get a cheap non-sks fob for me to use (I am not the primary driver) that I can program myself.

Or ... get the SKS one from eBay and try to get it fully activated. If the dealer can't use that one, buy one from the dealer, then use the eBay one as my personal key (with non functional SKS). That way, the eBay key is not a total bust.

I presume that any Toyota repair facility (dealer or not) can do the reprogramming with the proper equipment. The dealer is quite a distance out of the way from me, and there is a local shop that has done most of the maintenance

Unfortunately, it sounds like there is no way to be sure that a used SKS key can be fully reprogrammed to another Prius.

A couple more questions...

- Is there a list of the part numbers of the different year model fobs, so I know which one I am getting? What info can the seller retrieve from the fob to pass onto me?

- Should i be concerned that there is a SKS key fob (with no metal key...I still have that) "in the wild" that could start my car? Can the dealer remove the code for the lost fob from the immobilizer?

Thanks again.

--tom

 

The dealer can remove the lost fob from your immobilizer. The metal key will still work, unless you change the mechanical lock.

Tom

 

According to "bear68"...see top posting on this page :

http://priuschat.com/forums/prius-main-forum/35453-fob-problem-2.html

once an SKS fob has been programmed to a Prius, it can't be paired with another. The SKS programming works with the unlocking function, so the used fob is ONLY good for starting the car. The post is pretty convincing. He claims to be a "Toyota Certified Master Diagnostic Tech, Prius Certified".

If this is the case, it looks like my best option is to get a good deal on a brand new "virgin" SKS key to replace my lost one.

I'm also planning to get at least one cheapo fob for the starting function and program it myself. That one will be mine .

While I'm searching for a new key, it looks like there is a SKS key "in the wild" that is capable of starting my car. Thankfully, there are no identifying marks on it. Any way to protect myself from this short of having that key removed from the immobilizer?

Since I only lost the electronic part, it becomes useless once its' code is removed from the system (when I get the new fob programmed).

thanks,
tom

 

I've been reading up on the Keeloq encryption scheme that Toyota supposedly uses on the Prius keyfob.

When you press a key (or get a successful proximity detect), a counter is incremented in both the keyfob and in the car security computer. So a new keyfob will start with a low counter value, probably zero or one. Every time the keyfob is used, the 16 bit counter is incremented.

If the car security computer sees a counter value the same or lower than it has ever seen before from that keyfob, then it is rejected. This is done so that you couldn't record the sequence, and just replay the same signal again.

The car security computer can easily detect a used keyfob. The counter value is just higher than a new keyfob. The "add key" function obviously checks for too high a counter value, and rejects an otherwise perfectly ok keyfob.

This probably explains why used keyfobs typically cannot be added to a different car. The car security computer is programmed to reject an attempt to add a keyfob with too high a counter value.

But there do seem to be several exceptions. When I managed to delete one of my keys, it was possible to add it back using a scantool. The mechanic did the scantool procedure to delete all keys except the one in the keyslot. He then added back the deleted key, and attempted to add two other keys. The car accepted the addition of a used key that it had previously seen. The car rejected two other used keys, one silver, one black.

There is a possibility that a high counter value keyfob will also be accepted if the immobilizer is reset. I say this because of a long story about how a technician couldn't add a key. After an hour of fighting it, he made a phone call to his Toyota technical support center. They talked him through a special procedure, and it worked. My guess is that the special procedure was the immobilizer reset done when all keys are lost.