Kwikset 912 electric lock works for a while, then stops...

Discussion in 'Technical Repair' started by SpiderSpartanju, Oct 8, 2018.

  1. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    First a little background on me: I'm an EE, working in facility power, but I've designed and completed several low voltage projects professionally and at home. I have Raspberry Pis all over my house running everything from cameras to the garage door. Reverse engineering, however, is not something I've done much of. Now for my problem.

    I got a Kwikset 912 a while back and installed it on my garage. It powers up and works as expected for a while, but then stops. I can not seem to correlate what is causing the issue. Sometimes it works for a day, sometimes it several days. When it stops working I put my code in and it just freezes up. No attempt to turn the lock, no more beeping when I press the keypad, it just stops responding. If I pull the batteries for a couple hours, then put them in I get another day or 2 or 3 of operation before it does the same thing. They've sent me a replacement, so I can play around with this one and try to fix it. Any suggestions on where I should start?
     
  2. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    6,392
    1,485
    Do you need to remove the batteries for hours or will 10 seconds also 'fix' it?
     
  3. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    It seems like they have to be out for hours for the lock to come back to life. When I do a quick pull/replace, the lock beeps at me like it's back online, but remains unresponsive.
     
  4. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    6,392
    1,485
    What type of battery does it use?
    Stupid question alert: have you offered it some brand new batteries?
     
  5. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    I'm a true believer that there are no stupid questions, but yes I have replaced the batteries. It takes 4 AA batteries. I was initially using 4 rechargeable NiMH batteries and recently changed to the Energizer Ultimate Lithium batteries. No change in behavior.
     
  6. ericgibbs

    Moderator

    Jan 29, 2010
    5,722
    1,066
    hi,
    It is possible when it locks up, due to whatever cause, removing the batteries resets the device.
    The internal reset network may have a decay time constant of few tens of seconds.?
    Next time it locks up remove a battery, for say initially 10 seconds, check the units operation.

    E
     
  7. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    Pulling the batteries for seconds or minutes doesn't seem to have any impact. It will give me a startup beep and then be unresponsive, or do nothing at all. I did a search for kwikset on the forums before posting, but just did some more google searching and found the Teardown Tuesday: Kwikset SmartCode Lock article. One thing that caught my attention was the self-resetting poly fuse. I'm wondering if this may be what's causing the lock to die and then recover after a few days. Full disclosure, since the lock is "outdoor rated" I installed it and walked away, until it rained and I noticed water running down the inside of the door through the hole where the lock was installed.I took everything apart and it looked like it was dried out, but maybe I need to take a hair dryer/heat gun to it to make sure. I'll also look into checking that fuse. I'd welcome any other suggestions and will share what I can find out.
     
  8. ericgibbs

    Moderator

    Jan 29, 2010
    5,722
    1,066
    OK, thanks for the update.
    Lets know what you find.
    E
     
  9. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    6,392
    1,485
    Is it specified to use rechargeable AAs?
    The voltage is significantly less than alakline AAs. It might be worth trying it with four of them.
     
  10. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    I opened the lock up.The resistance across the polyfuse was 0.6 Ohms. I put the battery pack in and got a light, but nothing else. I did the reset procedure and the lock came back to life. I ran it without the ZWave card in, programmed a code, and ran through a lock/unlock sequence about 30 times. I'll try it again over the next few days and see what happens. The door that this is normally mounted on does get afternoon sun. I wonder if that might cause the polyfuse to break down in afternoon heat.

    Type of battery doesn't seem to have an impact (NiMH, Alkaline, Lithium).
    [​IMG] [​IMG]
    [​IMG]
     
  11. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    Day 2 and the lock is working fine on the bench. 20 cycles in the morning and 20 cycles in the afternoon and not 1 failure. I'll try again tomorrow and re-attach the zwave module for a few more days of testing. If that all works, I think maybe i'll leave a work lamp pointed at it for a bit to see if the issue is heat related.
     
  12. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
    6,392
    1,485
    If it is not now working the lock it may be drawing less current and that may be related to why it is working now.
     
  13. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    It's working the lock, just on the bench instead of mounted on the door. It could be drawing less current without the zwave module plugged in though. As long as it's still working tomorrow night i'll plug the zwave module back in and test it that way for a few days before testing it in some heat.

    I'm thinking maybe water got in and tripped the poly fuse. I read that once they trip they may never fully return to their original state. Maybe in the post-tripped state the heat of the sun is enough to trip it under normal amp draw.
     
  14. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    I think I've tracked the issue to the ZWave module. Ran through 20 more lock/unlock cycles this morning with no issue. Pulled the batteries, put the ZWave module in, replaced the batteries and the lock doesn't do anything.

    I think I'll pull the zwave module from the new lock and see if the original lock works with it or not, but at least the lock seems to work without it.[​IMG]
    [​IMG]
     
  15. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    Definitely the faulty zwave module "locking up" the entire lock. It works without the module in. I pulled a zwave module from a fully functional lock and it all works in this lock. So I have a new module on order and hopefully this lock will be back up and running in a week or so. Thanks for all the suggestions and ideas to help me fix this.
     
  16. ericgibbs

    Moderator

    Jan 29, 2010
    5,722
    1,066
    hi Spider,
    Thanks for the feedback, your findings may help other Kwikset users.
    Eric
     
  17. SpiderSpartanju

    Thread Starter Well-Known Member

    Apr 10, 2009
    59
    1
    Final update (I hope). I received the new ZWave card yesterday, put it in the lock, completed the inclusion process, and everything is working like new. If I ever get around to it I may try to troubleshoot the ZWave module, but chances of finding the time are pretty slim.
     
Loading...