Used Prius only came with Valet key. Big deal?

I've attached a couple of TSBs that relate to this subject. The bottom line is that if only a valet key is available, it is not possible to program the immobilizer ECU to recognize additional keys. It is required to replace the immobilizer ECU in order to accept new keys.

Regarding your effort to think outside the box, it is not practical to remove the immobilizer ECU functionality from the vehicle - unless you are familiar with digital circuits, take the time to understand the signals that the immobilizer ECU is providing to the hybrid vehicle ECU and the body ECU - then develop a black box that pretends to be the immobilizer ECU and allows the hybrid vehicle ECU to start the car.

 

Before you go replacing the immobilizer, it is possible to clone the key that you have.

Some locksmiths have the equipment to make a clone of a transponder key. The equipment reads the transponder data, and makes a copy that the immobilizer can't distinguish from the original key. Since your car already recognizes the original key, you don't have to program the car to accept the new key.

Here's a link to a site that sells the key to locksmiths: American Auto Lock The retail price of the key is $55, plus there may be an additional charge to program it. Finding the key is the easy part. Finding a locksmith with the cloning equipment could take some time.

 

The Jet part number for the clonable key is TR47-N-PHT.

Checking further, that site also says that they can do an immobilizer reset. You have to send them the immobilizer, so I guess the car is going to be out of service for a few days.

Here's the link to that page American Auto Lock

If you get the immobilizer reset, then you could use ordinary transponder keys instead of the special clonable version.

If you use their service, let us know how it works out.

 

An immobilizer is a computer in the car that is responsible for electronic validation of keys.

A transponder is a small electronic circuit in the head of the key. It has an identification number that is unique among all transponders.

When you put a transponder key in the ignition, there are two things that have to be validated. The first is the shape of the key, just like all other keys. The second thing that happens is that the immobilizer issues an electronic request to the transponder. The transponder replies with its identification number. This is limited to a range of about two inches.

The immobilizer has a list of transponder identifications that it accepts. Adding a key to the car consists of updating that list in the immobilizer.

Several companies in the locksmith industry have developed the ability to clone a transponder. This means that the duplicate key is really a duplicate - it has the same transponder identification as the original key. This has several advantages for a locksmith. The first is that he doesn't have to get access to the car in order to create a duplicate transponder key. The next is that there is no limit to the number of clone keys that can be created. The immobilizer typically has a limit of 4 or 5 different transponder identifications. But a cloned transponder appears to the immobilizer as if it is the original key.

The cloning process is strictly an aftermarket type of product. The car manufacturers never intended that it could be done. In fact they went to great lengths to prevent it. So you're not going see any Toyota documentation about how to clone a key. Since the equipment is expensive, only a few locksmiths have it. A particular locksmith may have equipment for only a few specific cars, and may refer you to another locksmith who has different equipment. I know that Jet claims to support the 2001-2003 Prius, and there may be others.

 

If in fact you can get the valet key cloned so that you have a couple of extras available, then that should be sufficient for all purposes except opening the trunk with the key.

 

Using the master key, it is possible to lock the trunk so that the floor-mounted lever does not function.

 

Right. The trunk/doors do not use the transponder, only the cut of the key.

One thing you could do is to have the trunk lock changed to accept the valet key that you have. If you can remove the trunk lock cylinder without using the key, then you could probably even do it yourself. Or take the cylinder and your valet key to a locksmith.

 

Most of this information is correct.

It *IS* possible to reprogram the Immobilizer ECU, but I believe it is a black market procedure. Somehow, the ECU software was leaked from Toyota and *A FEW* locksmiths who specialize in this stuff will be able to reprogram the Immobilizer. I had to get this procedure done on my car. It's not cheap, but far cheaper than replacing the ECU completely (to the tune of $1500, according to a quote from a Toyota dealer).

I was given only 1 key (master) with my 2002 Prius, and I lost it. I called various local locksmiths, and finally found one that could reflash the ECU. It was a 3 hour job and requires 2 people to finish it in a timely fashion, because the ECU unit is located deep inside the dashboard.

The best hope you have at this point is hope you never lose your key. If you do, you have no choice but to reflash the ECU or replace it. If you can get a master key cloned from the valet and it's cheaper than reflashing, I would say you should go ahead and get that done, because reflashing the ECU cost me about $500.

 

Doug Schaefer offered me a suggestion which fits the category of thinking "outside the box":

Cut off the transponder head on the existing valet key. Attach that head behind the dashboard so that it is hidden from view, and in range of the immobilizer ECU antenna. Now the immobilizer ECU should be happy.

Have a few mechanical keys made up, using the pattern from the valet key. Each of those mechanical keys should be able to start the Prius, since the transponder head has been attached to the inside of the dashboard in range of the immobilizer ECU.

 

No need to damage the original key. Just attach it intact near the ignition switch.

First you should get several non-transponder duplicate keys (about $2 each) at the local hardware store. Then try to start the car with the duplicate and the original transponder key near the lock. You need to find the range of the transponder. It's just a few inches, so you'll need to attach the key somewhere within range.

If there's no practical way to attach the key, you may want to consider an immobilizer bypass unit. You put a transponder key inside the bypass box, and run a wire from it to the antenna around the ignition lock. When power is applied to the bypass box, it relays signals between the box and the ignition lock antenna. The wire is generally easier to locate than the full size key.

There are also immobilizer bypass units that can learn your transponder code. They don't need the key once they've been set up. I don't know if there is a learning bypass box available for a Prius or not.

I do have a bypass box on my 2006 with a transponder from a keyfob in it. Some day it's going to be a remote start system, but for now it is just a spare key.

 

Doesn't that defeat the whole purpose of the immobilizer in the first place? Your car will be considerably less secure.

 

The people here in New Mexico steal cars by loading them in or on a trailer. So much for the smart keys. Good idea for taping the key to the steering column. My Toyota stealer wanted 600.00 minimum to replace the key ecu and cut the new masters.