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Key FOB programming help, went from SKS full function to Key in Slot only

Discussion in 'Gen 2 Prius Technical Discussion' started by Torquewrench, Nov 22, 2024 at 8:42 AM.

  1. Torquewrench

    Torquewrench Junior Member

    Joined:
    Mar 11, 2021
    5
    0
    0
    Location:
    California
    Vehicle:
    2006 Prius
    Model:
    II
    2006 Prius

    Before:
    Had a single SKS key with no RFID chip, I will call this KEY A. This key would start the car as long as it was NOT inserted into the slot and it would open all the doors, do all the SKS things.

    Plan/Intention:
    I want to add a second key and be able to start the car with SKS or with key in slot with both keys. The reason is when I have loaned the car to someone they will often try to put the key in the slot and then call me saying, "the car won't work!"

    Action taken:
    I tried the chicken dance. It would not work because my working key, KEY A, did not have an RFID and so inserting it 5 times into the slot and open/close driver door 6 times would not put it into program mode because of no RFID.

    I have Techstream and mini-VCI cable.
    1. Ordered RFID chiplet for KEY A, installed it in key
    2. Ordered second SKS key with RFID, I will call this KEY B
    3. Connected 12V battery to charger to avoid rundown during 16min programming
    4. IG-ON with KEY A not in slot, once car is on I inserted KEY A in slot so the RFID can be read
    5. Techstream detects the VIN and I chose "w Smart Key".
    6. Went to Immobilizer; Utility; Reset the Immobilizer
    7. Generated code from token purchased from one of the online sources, worked, 16min later process completed.
    Result:
    1. KEY A will no longer start the car, SKS or in slot (and it was the key in the slot during the programming) no
    2. KEY B (which was outside the car during IMMOBILIZER RESET programming) now works in slot to start the car.
    3. Security Indicator Light is SOLID when car is off, blinks in error pattern 2-2 when car is on and when driving. This blinking while driving is new and annoying.
    Next Action Taken:
    1. In Techstream in SKS section, did Smart Key Erasure using second token, 16min process, KEY B SKS works to open doors but not start car. It will still start car if inserted into slot.
    2. Did Smart Code Registration for KEY A, now both keys work to open doors, but neither key works to start car via SKS.
    3. Attempted to do Immobilizer Registration with KEY B, following instructions I remove it from slot, insert it into slot, go to IG-ON, hit next, but process errors out saying "Make sure battery voltage is at least 8V and car is set to IG-ON". Car is on a 12V 6A charger in addition to a fully charged 12V batt and the car is in IG-ON.
    Really puzzled and stuck! At least I have one key that will start the car, but I am worse off than when I started. Any ideas on what to try next? Maybe IMMOBILIZER RESET with KEY B which is now working to start the car when it is in the slot?

    Thank you!!!

    Torquewrench

    References:
    I have a bunch of references to the Priuschat threads I drew upon to learn enough do the above, but I'm not able to post them yet due to my status.
     
  2. Torquewrench

    Torquewrench Junior Member

    Joined:
    Mar 11, 2021
    5
    0
    0
    Location:
    California
    Vehicle:
    2006 Prius
    Model:
    II
    System Diagram from Repair Manual:

    Screenshot 2024-11-22 071405.png
     
  3. Torquewrench

    Torquewrench Junior Member

    Joined:
    Mar 11, 2021
    5
    0
    0
    Location:
    California
    Vehicle:
    2006 Prius
    Model:
    II
    From reading the Service Manual section EI - Engine Immobilizer, the Security Indicator Light staying on when KEY B is removed indicates the Transponder ECU is in registration mode aka programming mode. This is Part A of the Chicken Dance.

    With car off if I insert KEY B, the Security Indicator Light flashes with pattern 2-2, which indicates I am trying to register a key that has already been registered. Since KEY B will start the car when it is in the slot, this makes sense.

    Language from the manual: "Trying to reregister an already registered key will be cause code 2-2 to be output when the key is inserted." page EI-14, see first attached image below for code 2-2.

    When I insert KEY A, Security Indicator Light flashes with pattern 2-1, which indicates key code registration has failed in automatic key code registration mode.

    Language from the manual: "Trying to reregister an already registered key will be cause code 2-2 to be output when the key is inserted." page EI-14, see first image below for code 2-1.

    Reading further in the Service Manual, I think I have a next step (page EI-58, 59):

    (b) End automatic key code registration mode.
    Automatic key code registration mode can be forced
    to end when at least 1 key code (immobiliser code)
    for the key has been registered

    (1) Turn the power switch from ON (IG) and OFF 5
    times within 10 seconds using the already
    registered key.

    HINT:
    • When no key is inserted into the key slot in
    automatic key code registration mode, the
    security indicator light remains on.
    • When the immobilis
    er

    system is operating
    normally and the key is pulled out, the
    security indicator light blinks continuously.
    • If the key code registration has failed in
    automatic key code registration mode, code
    2-1 will be output from the security indicator
    light. Trying to reregister an already
    registered key will cause code 2-2 to be
    output when the key is inserted. If the
    number of registered key codes exceeds the
    limit, code 2-3 will be output from the
    security indicator light.

    I will try this and report back.

    Screenshot 2024-11-22 092526.png
    Screenshot 2024-11-22 105619.png
     
  4. Torquewrench

    Torquewrench Junior Member

    Joined:
    Mar 11, 2021
    5
    0
    0
    Location:
    California
    Vehicle:
    2006 Prius
    Model:
    II
    Thought I would post some Techstream images to make it clear what I am seeing and to help others:

    Screenshot 2024-11-22 072029.png Screenshot 2024-11-22 072155.png Screenshot 2024-11-22 072228.png Screenshot 2024-11-22 072307.png Screenshot 2024-11-22 072331.png Screenshot 2024-11-22 072417.png Screenshot 2024-11-22 072436.png Screenshot 2024-11-22 072829.png