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Certification ECU Question!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by darkgiant, Sep 22, 2015.

  1. darkgiant

    darkgiant Member

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    Hello All,

    My 2004 Prius is currently presenting the B2775 Error, I had made a thread about this few days ago, which can be found here: 2004 Prius Error Code Help! | PriusChat.

    After following the manuals posted by Toyota themselves, I was able to reset the Immobilizer code, and erase all smart keys on my Prius (as my main problem is that I am unable to lock, unlock, and wirelessly start the car. The car does turn on when I insert both fobs into the slot though). I am using Techstream Lite to perform all of these functions. For some reason, I cant' program the fobs onto the car (I also can't figure to find out where the Smart Indicator is...), but after going through the manual, it is starting to look like the Certification ECU is the culprit of the issue.

    My question here is that it seems like I would have to take apart much of the assembly of the steering wheel to get to the part, but is there proper documentation out there? Furthermore, are there other ways to test if the Certification ECU is the root of my key fob problem?

    How much would this part cost if is replaced? Unfortunately, this issue sounds unique to me, and I am assuming replacing this part would be a nice bill from the Toyota Dealer, which I am trying to avoid.

    Thanks!
     
    #1 darkgiant, Sep 22, 2015
  2. darkgiant

    darkgiant Member

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    BUMP! Looking for some help here!
     
    #2 darkgiant, Sep 22, 2015
  3. darkgiant

    darkgiant Member

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    Just an update here:

    So I ordered the Certification ECU/Smart Key ECU, I opened up the entire from assembly of the car, replaced the ECU, reprogrammed the Immobilizer, than both smart keys, and BOOM, it works!

    Both smart keys unlock and lock the doors, start the car keyless! To hell with the Toyota Stealership, the estimated $1700 price quote they gave me for first diagnosing the problem, replacing the part, and price of the part. All this required me is $15 for the Techinfo Account and $30 for the ECU, and a few hours to open up the car and understand how the entire Hybrid system works.

    Since this is a unique issue, I'll leave it to as it is, if anyone in the future runs into this issue, I can gladly help!

    Problem Solved! :)
     
    #3 darkgiant, Oct 3, 2015
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  4. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

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    Glad you are back on track!
     
    #4 ILuvMyPriusToo, Oct 4, 2015
  5. milleniaman

    milleniaman Junior Member

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    I read your solution to this problem and have a question. You finally replaced the smart key ecu; what about the certification ecu? Why didn't you replace this as that was indicated a possible source of the code? I have the same code along with 2796 which occurs when the key in the slot does not communicate with the transponder ecu. It seems to me this increases the likelihood that a transponder ecu replacement might resolve the issue. Could you please give me your opinion on the matter?
    JohnCaldwell
    p.s. The key slot problem has been a long standing problem. Swapping it did not change the codes.
     
    #5 milleniaman, Aug 9, 2016
  6. darkgiant

    darkgiant Member

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    I currently am away from my computer, but if I remember correctly, in the documentation (just google the error codes), there are several ways to diagnose what may most likely be the main issue in the car. I believe it was only having the Smart Key fob being able to only be plugged in, and unable to unlock/lock via the SKS system, nor start the car w/o plugging in the fob to diagnose it to be the SKS ECU. FYI - The Certification ECU = SKS ECU.

    As for your problem, I think it may be more than just the SKS/Certification ECU, as I remember correctly, the ECU that controls recognition of the key fob when plugging into the car is its own thing. It may most likely be the transponder ECU, but I am not sure if that is what you all it.

    A perfect way to get started would definitely be to check the Toyota documentation and follow their directions, it turns out you don't need to pay the $15 to get the TechInfo documentation, everything is available online if you search for it.

    I'd also recommend to get the Techstream software and try to reprogram the entire immobilizer, that gave me few clues to figure out which ECU could be potentially messed up.

    Best of luck!
     
    #6 darkgiant, Aug 9, 2016
  7. milleniaman

    milleniaman Junior Member

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    Thank you for this response. I'll pursue the techstream. :)
     
    #7 milleniaman, Aug 10, 2016
  8. darkgiant

    darkgiant Member

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    NP! Best of luck! If it does come down to having to replace the ECU, don't be afraid to look at eBay, you can even contact the seller directly and see if they can give you a cheaper price, it definitely works sometimes!
     
    #8 darkgiant, Aug 11, 2016
  9. fresno.prius

    fresno.prius Junior Member

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    I'd like to follow up on this thread. Just bought a 07 Prius w/ smart key from a friend. He had a B2796 code (no communication with transponder ECU) and dealer wanted $2200 to replace the transponder ECU, so he sold the car to me instead. I'll first try swapping the key slot with one from my 08 Prius to see if that is actually the problem. If not, I have a few questions about replacing the transponder ECU.

    1 Does someone have instructions on getting to the transponder ECU? I can't seem to find the exact location in the service manual and whether to work from the top of the dash down, or the bottom of the dash up, to get to it
    2 Which is better/easier/cheaper: replacing the transponder ECU with a new one ($280) and programming the existing two keys or replacing transponder ECU with a used one ($30) and programming new keys? I haven't tried programming Prius keys before so not sure what is invovled. I have Techstream lite but haven't played much with it other than have it open all four doors on one click of remote.

    Thanks for any help and advice!
    Ken
     
    #9 fresno.prius, Oct 7, 2018
  10. Dxta

    Dxta Senior Member

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    Pls you give some steps you followed to replaced the transponder eve?
     
    #10 Dxta, Oct 7, 2018
  11. darkgiant

    darkgiant Member

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    1. There isn't exact documentation on it, matter of fact when I did this, it is a bit like playing hide and seek. To give you an idea however, it is tucked behind the speedometer area, it is pretty easy to recognize compared to all the components. Once you recognize it, unbolt couple of screws, and plug out the wiring harness.
    2. I went with the used one, and to this day after three years it works just fine. For something like a transponder ECU I wouldn't personally splurge on a new one knowing it is a 2007 Prius, but that is your call. It's not like as if this part is an engine or something that is getting constant wear and tear that you'd want to get a less used/new one. Programming the keys is pretty straight forward as well. You'd need a key generator code (totally forgot what it is called) basically it is some site where you pay $30 and it generates like 5 codes that you plug into Techstream to use. I unfortunately don't remember the site from the top of my head at the moment but can look this up as I am currently mobile.
     
    #11 darkgiant, Oct 7, 2018
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  12. fresno.prius

    fresno.prius Junior Member

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    If you are trying to replace the transponder ECU (not the Smartkey ECU) its location is buried under the dash in front of the interior heater fan (towards the firewall), on the passenger side of the vehicle. This is NOT the Smartkey ECU location - that is in front of the steering wheel as described by darkgiant. To get to the Transponder ECU I took off the top of the dash, radio, center screen, and glovebox, then took off all the duct work for ventilation. The transponder ECU wiring is then visible coming from the HV ECU towards the firewall. You then need to loosen but not remove the heater/interior fan. Once you pull it back away from the firewall you can see the transponder/immobilizer ECU. After doing all that I just ordered a new one from Conicelli Toyota for $280. I hoping that I don't need to buy new key fobs since the transponder ECU is new. Does anyone know if you need new keys as well, if you have a new transponder ECU? I'm figuring that the transponder ECU will treat the keys as new since it does it is in new registration mode/is not programmed. According to the Toyota Electrical Manual (p. 05-2335)
    KEY REGISTRATION IN AUTOMATIC REGISTRATION (NEW REGISTRATION) . p 05–2335

    (a) When a key is inserted into the key slot, the key code (immobilizer code) registration is automatic. In this mode, a maximum of 5 key codes for 4 master keys and 1 sub–key can be registered. Any order of registration for the master keys and sub–keys is fine because the transponder key ECU can distinguish between different types of keys.

    HINT:
    S When a new transponder key ECU is installed, key codes (immobilizer codes) must be registered in the new transponder key ECU.
    S A new transponder key ECU is automatically set to automatic key code registration mode.

    I think after the key fob is programmed with the transponder ECU I need to then link it with the SmartKey ECU and the HV ECU. Seems like shorting the link between pin #4 and #13 in the OBDII connector for 30 minutes is the key to do this. I hope I don't screw something up even worse.....

    Anyway, the transponder ECU is supposed to arrive in the next day or two so hopefully it will all work. Wish it was the Smartkey ECU that was the problem - that sounds much easier!
     
    #12 fresno.prius, Oct 26, 2018
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  13. fresno.prius

    fresno.prius Junior Member

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    The new transponder ECU arrived and I plugged it in. The good news was that the immobilizer red light went solid, as it is supposed to when it goes into automatic programming mode. I also checked for the original B2796 code and it was no longer there, so I think the new ECU is working. But when I tried to put in my existing key that is tied to the old (non-working) transponder ECU and smart ECU the programming instructions did not work. The immobilizer light flashed 2 short and one long light, which translates to programming failed. So I think I need to buy a new smart key fob and try again
     
    #13 fresno.prius, Oct 27, 2018
  14. fresno.prius

    fresno.prius Junior Member

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    so I bought a new 'virgin' fob with SKS from ebay, inserted the brand new fob for 3 seconds or so and then took it out as the instructions said to do. Since I only bought one key that was it. Then I inserted a paperclip in pin #4 and #13 in the OBDII connector, pushed the power button to 'ON' with the brake, and let the car sit for 30 minutes (with a trickle charger attached to the 12v battery). After that I turned off the power button, pulled out the paperclip, then pushed the power button with my foot on the brake and the car started without a hitch. Wow! Remember this was with a brand new transponder ECU ($275) and a new virgin SKS fob ($165). So now the new fob works in the slot. This is definitely one option if you lose both your keys - not sure if it is the cheapest or easiest becaue you have to get to the transponder ECU, but it definitely works with no techstream, no dealer, no computer. Don't tell the thieves....

    Now I want to program the remote and the SKS system to the new fob. Since it is a new fob can I just get the 6 digit code from website that does the pincode calculator to reset the smart key system and link my new key with the existing smartkey ECU, since it is working fine? As an aside, at this point I have a wierd situation. My old fobs unlock the door both with the remote buttons and door handle SKS button. The new fob doesn't (yet) unlock the door with either system but it starts the car with the fob in the slot. Wierd. Ken
     
    #14 fresno.prius, Oct 30, 2018
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