Key fob lost programming?

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by bengreen55, Jul 24, 2022.

  1. bengreen55

    bengreen55 Junior Member

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    Vehicle:
    2014 Prius v wagon
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    Two
    Hi. I hadn't driven my 2014 V for close to a week. When I went out to open the door and drive it, there was no response touching the door handle or pressing unlock on the key fob. I did mechanical door entry and tried to start but no lights on display. Totally dead. So connected my portable start battery (Viking, highly recommend it) to the fuse box jump tab and engine block. Started the car...and all mayhem broke loose.

    Alarm sounded. Key fob would not silence it. Drove my neighbors nuts next half hour trouble shooting.

    So alarm would sound (30 seconds each time), dashboard flash it's display and engine would start but wouldn't drive. Each time door was opened/closed or I jostled something inside, alarm started again. I put a fresh battery in the fob. Tried my second fob. Tried putting alarm (Karr) in valet mode (5 second press of button under dash per Karr emergency operator direction). Nothing worked. Door locks still didn't respond. I gave up and went inside.

    After a half hour, I rembered I had left one of the fobs in the car. Went out to get it, cringing at thought of disturbing my neighbors again. Manually opened door...no alarm. Pressed brake and power button...car started normally, ready to drive.

    What I'm wondering is, does the car "forget" the key fob after 12V battery is dead for a while? Did leaving the fob in the car give it the time it needed to get reacquainted with the car and do a proper handshake?

    BTW, the traction battery hadn't drained at all. It was indicating 8 bars immediately after the jump start.
     
    #1 bengreen55, Jul 24, 2022
    Last edited: Jul 24, 2022
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    I had this type of problem, the first thing I would do is completely (and permanently) remove the aftermarket alarm system. Those systems can get weird after 5-10 years.

    Posted via the PriusChat mobile app.
     
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  3. bengreen55

    bengreen55 Junior Member

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    Vehicle:
    2014 Prius v wagon
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    Two
    Thanks. Don't think it might be 12 volt battery issue? They start getting worn on same time scale. Been using car's onboard test screen (Press Start 2x without brakes for Acc / Press & Hold any display button / Flash headlights on and off 3x) to see battery volts. Unloaded 12v / Load 11.7v. So it's time for new battery.
     
  4. bisco

    bisco cookie crumbler

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    i would say you need a new 12v. you can have it tested free at any auto parts store, but if it's over 6 years old, i'd just replace it.
    however, that may not be the problem. you'll find ou when you replace it, but sometimes boards get fried when they are reconnected to 12v, and that may have happened to your alarm, or it could be another issue with the alarm.
    is the alarm designed to prevent the car from starting? if it is working mormally now, you probably just need the 12v.
    computers don't forget the keyfob even without power.
     
  5. bengreen55

    bengreen55 Junior Member

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    Location:
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    Vehicle:
    2014 Prius v wagon
    Model:
    Two
    Went ahead and replaced 12v battery. All seems normal. Thanks for responses.

    BTW If you buy the OEM TrueStart battery online it's discounted from the MSRP of $231. This blog won't let me give the url but if you search for TrueStart Prius battery and use the site that has only parts and toyota in the title, you're there.

    First time I checked, it was $196. Dithered. Second time $199. Stopped dithering, bought it. Picked it up at my local dealer. No shipping charge (because essentially you're buying it from the dealer via an online portal).

    It helps if you know the part number because the lookup isn't the best.
     
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