The 2004 & newer Prius uses a "Smart Key" that allows the owner to open and start their car without even removing the key from their pocket. Pretty neat. But what happens if you lose your smart key? Well, the replacement key costs about $200, then it must be programed to work with your car, or more accurately your car must be programed to work with it. The photo log below outlines the process.

 
The first items you'll need is one smart key that works with the car and one replacement smart key. If you have lost *all* of the smart keys, a seed value must be obtained using the dealer-only version of TIS, which means you'll have to tow the car to the dealer to reset the key transponder ECU. The smart key has an emergency "standard key" insert that can be pulled from the smart key body in case the 12 volt battery goes dead. The new smart key insert is blank, and needs to be cut to mach the locks on the car.

 

The next item you'll need is the Toyota or MasterTech scan tool. These are still fairly expensive, and make this project out of reach for all but the most hardcore do-it-yourselfers. The Toyota scan tool can be purchased from SPX/OTC though the Toyota technical webite --

http://techinfo.toyota.com

The MasterTech can be purchased from Vetronix --

http://www.vetronix.com/

The Toyota scanner may lack some of the generic OBDII features the MasterTech has. The MasterTech will function exactly as the Toyota scanner provided genuine Toyota software is used.

 

 
I don't know if the Vetronix Toyota card has Imobilizer function. We purchased our card directly from Toyota.

 
The 2004 Prius was the first Toyota to use CAN (Car Area Network) interface. The Toyota scanner will not work with a CAN car without the CAN interface module. The CAN interface module can be left in place when using the scanner for earlier non-CAN Toyotas; however, it must be removed before using the scanner for generic OBDII or using the Honda card.

 

I learned a leason during my nearly disasterous experience registering RFID keys on the first generation Prius:

** NEVER DO ANYTHING THAT REQUIRES KEY ON POWER WITHOUT A CHARGER HOOKED UP **

The 12 volt glass mat battery does not start the car, so there is no observible symptom when the battery goes bad. There are many Priui are driving around with bad 12 volt batteries, unbeknownst to their owners. The last thing you want to happen while writing to any ECU is the power to go out! Hook up the charger and you'll save yourself a lot of grief. The Prius requires a special charger to prevent damage to the battery. It can be purchased from Toyota and is not very expensive. I asked an Interstate battery rep if using the wrong type of charger would really cause damage. He said it likely would, because the plates in glass mat batteries tend to "swell" when charging, and charging at conventional battery charging voltages could cause the plates to touch and short out.

 

Tape the instructions where you can read them.

 
The scanner gets the registration process started, then we follow the flow chart. It's easier than tapping out a pattern with the door latch switch.

 

This is the switch to turn off the smart key function. When this switch is pressed, the unlock & lock buttons on the on the smart key must be pressed to unlock & lock the doors, and the smart key must be inserted into the smart key slot to start the car. Once the key is registered, we check to make sure the key registration worked by turning off the smart key function and starting the car with each of keys in the key slot. It may also be a good idea to check the smart key function of each key by moving one smart key out of range at a time, since we had one customer complain that their new smart key worked only in non-smart key mode after we registered it. He never brought the car back for us to check, so we don't know what went wrong. We have not seen a similar case since.