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Smart System / FOB problem?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Paul_G, Dec 13, 2019.

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  1. Paul_G

    Paul_G Junior Member

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    Totally new here, sorry for sounding like an idiot... it comes naturaly.

    I could use a little help.... I just bought a 2006 Prius that has the smart system stuff in it. I had no idea what this was when I bought it. When I first bought it, the car would only power on & power off with the FOB inserted into the slot..as if the battery were dead. Then all of a sudden, the smart system stuff started working...the car would unlock by pushing the button on the handle, and it would power on & drive with the FOB in my pocket or somewhere else in the car other than the slot. That worked for a few hours and now it doesn't work again and hasn't worked in 2 weeks. I bought another used FOB and did part 1 of that chicken dance routine (insert/remove the FOB 5 times, open/shut door 6 times....etc) to get it paired with the car...now that FOB powers on and off the car fine, however the 2nd half of getting the lock/unlock buttons paired does not work...even though the doors locked & unlocked at the end which supposedly indicates success....but it does not work.... it only powers on & off the car and allows me to drive it.

    The batteries are good and I'm not pushing that button under the steering wheel....so neither of these are the problem

    I asked the local Toyota dealer what he thinks the problem might be, and more than 1 person there said it's most likely a bad key FOB. 2 fellas there said in dealing with the Prius for 15+ years, they've never heard of the smart system going bad. I'm trying to avoid paying another $200+ to buy a new FOB and have it programmed...but it's not looking promising.

    I currently have 1 FOB that locks & unlocks the door using the buttons, as well as powers on & off the car while in the key slot, and 1 FOB that only powers on & off the car

    So I guess my questions are .... #1 Has anyone ever heard of the smart system going bad? I've read that it's possible the 12v battery is bad, but from my reading up on this, there would be other indicators if that was the case. And #2 Is there any way to troubleshoot this problem without paying $200+ to buy a new key fob and have it programmed? If I get a brand new FOB programmed and it doesn't work, then there's something else going on and I'll deal with it then.

    Any help is appreciated.
     
    #1 Paul_G, Dec 13, 2019
  2. bisco

    bisco cookie crumbler

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    congrats and welcome!
    i have never heard of it going bad. it is possible that the ecu is defective, or a loose connection somewhere. maybe even the sks button.

    but i would start with the 12v and fob batteries. if you're going to diy, learn how to load test them with a simple digital volt meter.
    if they are good, the tough stuff comes after.

    what i have read is that reprogramming fobs can be tricky, so don't ignore that possibility.
     
    #2 bisco, Dec 13, 2019
  3. dolj

    dolj Senior Member

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    There is an SKS disable button below the steering wheel column which is labelled "Key". Check to make sure this is in the "out" position.

    When the button is pressed in, SKS is disabled. When the button is pressed again and toggled to the "out" position, SKS is re-enabled.

    This sounds like a likely cause of your issues, even though you said, "you not pushing that button under the steering wheel." It would be good to double-check that it is in the correct position (out).

    BTW, pressing the button on the door handle locks the car. You unlock it by touching the inside of the door handle.
     
    #3 dolj, Dec 13, 2019
    Last edited: Dec 14, 2019
  4. SFO

    SFO Senior Member

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    Welcome to PriusChat!!
    Will do my best, if only by dragging @RobH into the discussion.
     
    #4 SFO, Dec 14, 2019
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  5. Paul_G

    Paul_G Junior Member

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    That's not it. The button seems to work as it should, but that is not the problem I'm having.
     
    #5 Paul_G, Dec 14, 2019
  6. RobH

    RobH Senior Member

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    There is a red LED that flashes when you press a button on the FOB. If there's no flash, then the FOB battery needs to be replaced. The rubber buttons on an old FOB can degrade to the point that they jam ON, which will wear out the battery in short order. Replacement cases are available for $10 or so. I'd recommend a replacement case, and a fresh battery. Be sure to move the transponder (a black chip about 1/8" x 1/8" x 1/2") as well as the separate circuit board over to the new case. The original FOB case is glued - separate it with needle nose pliers spread in the mechanical key slot. Replacement cases just click together.

    There are three lock mechanisms used on Gen2 Prius. The key-in-slot uses a transponder chip in the FOB that works without the battery. Both silver and black logo FOBs use the same transponder mechanism. The short chicken dance will program both new and old FOBs.

    The button/proximity mechanisms are different between SKS and basic cars. The longer chicken dance can be used to program a new silver logo FOB. A used FOB is going to require Techstream with security authority. Some locksmiths have equipment that can handle used FOBs, so it's worth calling around. There are services that reset a used fob to new condition, but I've only seen them for GEN3+, not for GEN2 like we're talking about here.

    The third lock mechanism is the mechanical key. It will get you in the door, but it won't start the car. Duplicates can be made on ordinary Toyota key blanks.
     
    #6 RobH, Dec 14, 2019
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  7. Paul_G

    Paul_G Junior Member

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    Thanks for the replies. I paid a fella with some programming gizmo to try and program one of my new/used FOBs, and it failed, which he says is a sign that the smart system is bad somewhere. He confirmed that the FOB that came with my car is good and is properly programmed (even though it eats a battery every few days). All of my FOBs are transmitting on 312 MHz as they should.

    Now I've got to figure out where the fault is with this smart system and I have no clue where to start. Time to read up on it.... perhaps someone can point me to a thread with a similar problem?
     
    #7 Paul_G, Dec 17, 2019
  8. RobH

    RobH Senior Member

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    Part of programming a used fob is waiting about 15 minutes while the reset takes place. If that didn't happen, then the reset didn't happen. The car has to be reset back to zero fobs, and then the used fob must be the first fob reregistered. Then reregister the one that was working. Resetting to zero fobs requires a security seed.

    As for eating batteries, I still think the fob case needs to be replaced. The rubber buttons degrade and they can jam ON, causing battery drain. If that's intermittent, then the problem with sensing the fob is intermittent.
     
    #8 RobH, Dec 17, 2019
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  9. Paul_G

    Paul_G Junior Member

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    This did the trick Rob.... I got a new case, transplanted the board & chip and it seems to be working as it should now.

    Another question.... when I go through the chicken dance to program another FOB, I can get it to start & stop the car with the FOB in the slot (which seems to be programming the chip), but when I try the 2nd part to get the door lock/unlock working * SKS functionality working, I get through the whole process, hold down the LOCK button for 2 seconds and instead of cycling the door locks once, it cycles twice - which seems to indicate failure...either the FOBs are no good or the batteries are low? Or there are too many FOBs programmed. I've tried many times and get the same thing each time. I know the batteries are good.

    The FOBs that I have do have buttons that are pretty degraded. Is it possible that the FOBs are experiencing the same problem that my initial FOB had with the degraded button causing the problem? Could that be preventing them from being programmed / paired?

    Is there a way to tell how many FOBs are programmed? I've looked but can't find an answer. If there are too many, is there any way that I can clear out all of the non-working FOBs without paying a locksmith / programmer dude to do it?
     
    #9 Paul_G, Jan 3, 2020
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