How to Repair a Prius Smart Key

Written by teresa rodriguez
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How to Repair a Prius Smart Key
(Creatas/Creatas/Getty Images)

Repairing a Prius smart key is usually an issue of programming. Lost or inactivate smart keys must be reprogrammed to activate their functions. This generally requires the use of specialised diagnostic tools that are available only at a Toyota dealership. You can perform the job yourself as long as you have one original key fob. Performing a series of steps will allow the smart-key fob, which has a silver Toyota logo on it, to operate the ignition and door locks, and remotely unlock and start a 2004 to 2009 Toyota Prius.

Skill level:
Moderately Challenging

Things you need

  • Toyota diagnostic tester kit
  • CAN interface module kit
  • 12-MB diagnostic tester program card

Show MoreHide


    Starting the Prius

  1. 1

    Insert your old fob into the ignition slot, then remove it. Do this four more times in a row, leaving the key fob in the dash the fifth time.

  2. 2

    Open and close the driver's door six times.

  3. 3

    Remove the old original key fob from the ignition slot. The Prius is now in fob programming mode.

  4. 4

    Insert a new fob into the ignition slot. Leave it inserted for 60 seconds. Watch the blinking red dashboard light until it stops blinking. At that point, the new fob is programmed.

  5. 5

    Remove the new fob. Test both fobs to double-check that they work correctly.

    Remotely Unlocking/Locking the Doors

  1. 1

    Open the driver's door.

  2. 2

    Insert your original fob into the ignition slot and remove it. Do this twice within five seconds.

  3. 3

    Close and open the driver's door twice.

  4. 4

    Insert and remove the original fob once. Close and open the driver's door twice again.

  5. 5

    Insert the original fob and close the driver's door.

  6. 6

    Press the Prius power button without pressing the brake pedal. Wait one second, then press the power button a second time. Wait one second, then press the power button a third time to power off the car.

  7. 7

    Remove the original fob from the slot. The Prius is now in "add mode." The Prius should lock and unlock the doors twice to signal that "add mode" is active.

  8. 8

    Press and hold both buttons simultaneously on the new fob for one and a half seconds. Within three seconds, press the fob's lock button. The Prius responds with one lock/unlock sequence if programming is successful. If the car locks and unlocks twice, the programming was successful.

  9. 9

    Exit "add mode" by opening the driver's door or inserting the fob into the ignition slot.

Tips and warnings

  • The most common and easiest to diagnose "failure" of the smart-key system is the inadvertent pressing of the smart-key button on the dash. The driver must press the smart-key unlock button to get into the car, and must also insert the key into the smart-key slot to start the car. Checking this first before signing the car in can save you from the expense and time of a Smart Key "repair".
  • For smart-key functions of remote unlock and start without touching the fob, the programming must be done at a dealership with the diagnostic tools and interface card.

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