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Where are the key codes stored?

Discussion in 'Gen 2 Prius Technical Discussion' started by NarklepticSnipr, Mar 23, 2021.

  1. NarklepticSnipr

    NarklepticSnipr New Member

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    Somehow BOTH of my fobs went missing for my 2k7 without proximity entry. I have the metal key to allow me into my car but I can’t move it.
    Does the ECM store the key codes and can I erase them? What’s the easiest (lol) way to put the car into auto learn mode so I can program new transponder chips?
    I’ve pulled the ECM board with the hopes of identifying the EEPROM that has the codes but no dice. Maybe my eyes are going bad?
    Help?
     

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  2. PriusCamper

    PriusCamper Senior Member

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    Toyota Techstream software running on an old Window's computer via a Mini-VCI dongle will give you access to adding a brand new Key FOB. As long as you haven't reached the limit on number of FOBS associated with the car you can add more. If you are at the limit or want to use some used FOBS, you'll need to pay a service in Europe that will give you an access code based on your VIN#, which will allow you to use Toyota Techstream to wipe all FOBS from the system and re-seed new ones.
     
  3. NarklepticSnipr

    NarklepticSnipr New Member

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    Ok, so out the board and ECM back and go the TIS route. Got it.
     
  4. Tombukt2

    Tombukt2 Senior Member

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    maybe in chip in slot that holds remote or you dont have this . i se this option in techstream. havent tried it,,
     
  5. NarklepticSnipr

    NarklepticSnipr New Member

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    I’ve seen videos of other Toyota ecus being virginized to allow the system to autolearn new keys. Requires you to pull the board and access the eeprom memory and reformat it. Didn’t know if anyone knew of that here in the Prius.
     
  6. dolj

    dolj Senior Member

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    There is no "chip in the slot", so that's a no.
     
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    How can Techstream add a key when all keys are lost?
    Isn't reseed the only option at this point?

    Posted via the PriusChat mobile app.
     
  8. Elektroingenieur

    Elektroingenieur Senior Member

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    No, on 2004–2009 Prius models without Smart Key, the key codes are stored in the transponder key ECU for the immobilizer function, and in the door control receiver for the wireless entry function, according to Toyota’s Smart Key System: Course T973B Handbook (available by subscription to techinfo.toyota.com).
    As @PriusCamper kindly pointed out, the Smart Code Reset procedure (which I discussed in December 2019, January 2020, and December 2020) was developed for just this “all keys lost” situation.

    This avoids the need to replace the transponder key ECU, which is mounted inside the instrument panel behind the air conditioner, presumably as a theft deterrent, to make replacement difficult and time-consuming.
     
    PriusCamper likes this.