Prius 2006 SKS key - Not Un-locking driver's door or starting car

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by DashingDave, Dec 27, 2024.

  1. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Can you help please?

    Prius 2006, Gen 2 with SKS key

    Problems --
    Key stopped Un-locking driver's door or starting car.

    Clues --
    * Pushing start button without key in slot - triggers Key missing light on Dash
    * Pushing start button with key in Slot - Key-missing light on Dash does NOT light up.

    Meaning key is recognized, and
    Key is recognized as Valid - otherwise key light would not have gone out.

    All 4 Door locks work on & off from Drivers seat door lock switch
    When unlocked tail hatch opens (thank goodness)

    Key Does not unlock any doors from Drivers door outside
    Key Does not unlock any doors from Passenger door outside
    Key Does not unlock any doors from Tail Hatch outside

    Conditions-
    So 12volt battery is reasonably verified as charged -
    also it was on charger giving me a FULL Charge reading just before its final trip.

    * Fob key battery is verified good @ 3.12volts (ed:
    Update -- There is no 2nd FOB).
    * HV battery is mid range charged
    * Key is Valid
    * SKS System recognizes Key when in slot.


    Tried and unsuccessful --
    All (underhood and under dash drivers side) Fuses checked and visually good
    Disconnected battery and shorted the two + and - cables while counting to 10.

    Until car is running - Cannot check --
    * Head-lights, or
    * Turn signals, etc.

    Thank you for reading this
     
    #1 DashingDave, Dec 27, 2024
    Last edited: Dec 28, 2024
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,542
    50,243
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    do you have a second fob?

    put a fresh battery in the fob, make sure it tests 3.3v first

    have the 12v load tested for free at most auto parts stores
     
  3. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
    7,912
    4,005
    0
    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    Have you checked each of the buttons on the fob is not sticking in the "down" position. Do you hear an active "click" on each button when you depress it and observe the red light lighting up in response to each push?
     
    #3 dolj, Dec 28, 2024
    Last edited: Dec 28, 2024
  4. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Thank you for responding.
    Re FOB battery --
    No 2nd Fob.
    I'll put new battery in and make sure its 3.3. Will report back.

    Re Load Test 12 volt --
    Since I can't start the car - can't easily get it to an Auto Parts store.
    Don't have a second car and its 15 miles out in country.
    Yes, I could take battery out and borrow a car.

    But I'm fairly familiar with a low 12 volt - and it has none of those symptoms - indeed
    it acts the opposite. Just as in fully charged - It enthusiastically locks and unlocks doors.
    Besides that the 12volt started the car easily the last time.
    I was just charging it because I wanted to top it off.
    And the very reliable charger reported a full charge just previous to the last start.
    I'll keep that as a last resort.
    In interim, I'll check 12v battery voltage.
     
    bisco likes this.
  5. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Thank you for rapid response.
    Yes, checked each of 3 buttons. All provide a clear click.
    Even took fob apart to see if anything was amiss. All looks good. No buttons sticking.
     
  6. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
    7,912
    4,005
    0
    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    You can't really equate these two things as they are two separate functions.

    The former is really a clue as to why the key is not recognized when not in the slot. I believe there are two receivers that are used to detect the key when inside the car.

    The latter confirms the RFID is detected and registered to the car. This is so the car can still be started when the CR2032 battery is flat. For the sake of completeness, can you confirm the car starts when Start Button is pressed in this scenario?
    Can you confirm you mean pressing the rubber pad (to lock) and touching the back of the front door handles or pressing the hatch release button/lever (to unlock) – SKS function; or when using the lock/unlock buttons on the key fob – Remote function; or both. Again, these are two separate functions so the fact they both don't work is interesting. While on this subject, is the "Key" button (which disables the SKS), below the steering column, in the 'OUT' position, meaning the SKS is not disabled?

    One other thought I had, are you sure the new battery is installed in the correct orientation? That is, with the + side up.
    upload_2024-12-28_20-31-30.png
    In the illustration in the owner's manual, to me, it looks like the negative side is up, so just checking.
    upload_2024-12-28_20-35-1.png
     
    #6 dolj, Dec 28, 2024
    Last edited: Dec 28, 2024
  7. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,542
    50,243
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    If you opened the fob, make sure the chip didn’t fall out
     
  8. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Thank you Bisco and Dolj for trying to help !

    The 12 volt battery is charged to 12.74 volts - with cables disconnected.

    "can you confirm the car starts when Start Button is pressed in this scenario?"

    A: The car does not start under any tested circumstances.

    FOB --
    A: FOB chip did not fall out

    A: FOB battery is new @ 3.34volts

    A: FOB battery is correct side up

    A: The chip is inside FOB in the proper position.

    A: Yes, Pressing the rubber pad (to lock) and touching the back of the front door handles
    or pressing the hatch release button/lever (to unlock) – SKS function - does nothing.

    A: And when "using the lock/unlock buttons on the key fob – Remote function; or both" - does nothing.

    SKS Key button
    A: "the 'Key' button (which disables the SKS), below the steering column, is in the 'OUT' position, meaning the SKS is not disabled"

    Opinion:
    My current rough diagnosis considering all the evidence is that
    the problem is not the FOB,
    but the SKS system inside the car.

    For me the revealing clue is that the SKS system recognizes the key, and recognizes it as valid.
    Yet - somehow it the SKS system won't allow the computer system to start (to initiate car start).

    Q: Are there any hidden Fuses that might affect this?
     
    #8 DashingDave, Dec 28, 2024
    Last edited: Dec 28, 2024
  9. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,542
    50,243
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    one possibility might be corrosion on the sks ecu connectors. idk if there's anything on the net, or if you would need the service manual to locate it
     
  10. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Thanks again for trying Bisco. I'll see what I can turn up.

    Where could I find the Shop Manual for the Gen2 Prius - that would cover this?

    or even better the Diagnostic Flow Charts that the engineers and mechanics use to Diagnose this rapidly.

    The big reason I need those is because this is a strange problem (but possibly something simple) -
    it is highly unlikely the local Toyota dealer head mechanic would know any more than we do.

    But the Toyota Engineers who designed the SKS system know exactly how it all works.
     
    #10 DashingDave, Dec 28, 2024
    Last edited: Dec 28, 2024
  11. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,542
    50,243
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    techinfo.toyota.com
     
    DashingDave likes this.
  12. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    3,765
    1,774
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    Does the dome light work? (Might want to check all fuses in the underhood and underdash fuse blocks).

    Does the little red LED on the fob light up when you push a button on it?

    Do you know that the dash slot works? When was the last time you used that?

    IDK that having the security light out with a fob in the slot absolutely means that the immobilizer has recognized the RFID chip. (separate system from SKS)

    This is the RFID chip.

    Screenshot_20240123-123627.jpeg

    Posted via the PriusChat mobile app.
     
    DashingDave likes this.
  13. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Thank you Mr.GuyMann for posting the pictures of the RFID chip and its location.
    Very Helpful ! Especially as I've never seen the RFID chip before - and have opened
    the fob many times and changed the Fob once, about a year ago.

    RFID FOB CHIP MISSING
    Bewilderingly - the RFID chip is missing from my FOB.
    So this immediately jumps up as a Suspect for the problem. However...

    Car had been starting just fine for many months, maybe a year - since I replaced the shell.
    It has wirelessly opened the driver and passenger doors and rear hatch.
    It always started the Gen2 - in or out of the Slot.

    The fob had not been disassembled for months before this failure.
    Then 3 days ago it would not open doors or start the car.
    This was hours before I took the fob apart to check its batteries - when potentially the RFID fell out.

    So for a solid year - the RFID chip has either been in the FOB - or it hasn't.
    I do not recall anything falling out when I checked and changed the batteries two days ago - AFTER the starting failures.

    According to DOLJ --
    "The only thing that will not work if you do not transfer the RFID chip over,
    is starting the car with the fob inserted in the dash.
    -- May 27, 2017

    Other Symptoms:
    Q: Does the dome light work? (Might want to check all fuses in the underhood and underdash fuse blocks).
    A: Yes, dome lights work. All fuses (underhood and underdash) were checked as visually good.

    Q: Does the little red LED on the fob light up when you push a button on it?
    A: No. There has never been a red LED light on the fob. The key has worked for years without it.
    I did install a new 3rd party fob case about a year or so ago.

    Q: Do you know that the dash slot works? When was the last time you used that?
    A: Yes, Dash slot has been working as recently as a month or so.
     
    #13 DashingDave, Dec 30, 2024
    Last edited: Dec 30, 2024
  14. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Could the FOB programming have been damaged by something like static electricity?
     
  15. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    3,765
    1,774
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    Maybe the RFID chip wasn't swapped with the new fob case, and the car has only been using the SKS since then. Until now.

    Every working Gen2 fob I have seen has a small LED that flashes when you push a button.
     

    Attached Files:

  16. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    3,765
    1,774
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    The point is that if you only have the one fob then now you are facing an "all keys lost" scenario.

    You would need to have a capable (mobile) locksmith reset the immobilizer and SKS ecu's then program replacement fobs.

    Or tow the car to a dealer.

    A few here have done this DIY but that requires a capable (OE level) scantool that handles immobilizer functions. Then dealing with some site in Europe to buy "tokens" and use them to generate a "seed code" based on your VIN that will reset things.
    Use the search function as I have never tried doing this.

    Posted via the PriusChat mobile app.
     
    DashingDave likes this.
  17. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    That's possibly the most helpful clue so far.
    Thank you
     
  18. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Thanks again.
    I've read about the DIY options. Can probably get the TIS scan tool and cable. Might be a lot less expensive than our local Toyota
     
  19. DashingDave

    DashingDave Junior Member

    Joined:
    Feb 15, 2020
    26
    6
    0
    Location:
    Monterey
    Vehicle:
    2006 Prius
    Model:
    II
    Monterey, Calif Toyota dealer - just quoted me $850 for Key (~300) plus 2 hours (right ! ) of mechanics' time.
    This is because they have no competition within 25 miles. "We don't care, because we don't have to."
     
  20. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,542
    50,243
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    that's pretty much the scenario since covid