Cold Weather Car Won't Lock/Unlock

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by JetAgeHobo, Jan 3, 2012.

  1. JetAgeHobo

    JetAgeHobo Junior Member

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    Second time I've had this problem this winter. 2007 Prius, about 65K miles. When the outside temps go below 20 or so the car locks seem to not want to work. For example this morning temp was about 19, smartkey unlocked the car ok-took a couple of button pushes but it worked. Car started fine. Drove to work and after shut down couldn't lock the car. Smartkey didn't work, pushing the door button didn't work. Lock switch inside the car works, so I locked the doors except driver's then used the manual key to lock the driver's door.

    Any ideas? I've checked the battery using the internal maintenance screens, no load voltage about 12.3V, Load voltage 11.7Volts, Charging voltage 14.3 volts. I know I'm due for a 12V battery with it being 5 years old and such, and I'm pretty sure a good cold day will kill it dead. But, other than the battery, any suggestions?
     
    #1 JetAgeHobo, Jan 3, 2012
  2. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    frost on sensor??
     
    #2 DaveinOlyWA, Jan 3, 2012
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Replace the 12V battery.
    2. Replace the fob battery.
     
    #3 Patrick Wong, Jan 3, 2012
  4. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    ooops, no sensor. missed the "button" part. its probably the battery. it gets cold, battery capacity drops.
     
    #4 DaveinOlyWA, Jan 3, 2012
  5. Hal W

    Hal W New Member

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    Weak 12v. Hal
     
    #5 Hal W, Jan 3, 2012
  6. googrx

    googrx New Member

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    If you can start the car, how can it be the aux battery? if you can't, then it probably the aux battery.
    It probably your fob key and or its cell battery, or you turn off the smart keyless system.
    I turned off mine all the time, to spare the battery power since this thing scan for the fob key all the time, wasting energy.

    Speaking of fob keys, do you know how many keys are made for each car? do they have it on record?
     
    #6 googrx, Jan 3, 2012
  7. JetAgeHobo

    JetAgeHobo Junior Member

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    Worked ok going to lunch. (temp in low 30's) and going home (temp in mid 30's) I would have thought if it was various batteries I wouldn't be able to unlock the car first thing in the morning after the car has been sitting outside all night, not after the car has been run, battery recharged from trip.

    If fob battery, (which is entirely possible) would the proximity sensor not work? Like I said, lock/unlock door buttons don't work when this happens also.

    Not turning off smart key system.

    See how it goes next few days.
    Cheers
     
    #7 JetAgeHobo, Jan 3, 2012
  8. Dutch

    Dutch Junior Member

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    Frost on mechanical parts? There are still mechanical linkages at work - perhaps they have some condensation on them that is freezing up. Would fit the scenario of being worse after driving to work, with outside parts getting even colder from air flow. I used to carry a little squirt bottle of alcohol for mechanical key locks for those bitter cold winter days when the lock mechanism was frozen. Might be worth squirting some alcohol through the key flap. What do you think?
     
    #8 Dutch, Jan 3, 2012
    1 person likes this.
  9. JimN

    JimN Let the games begin!

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    A weak 12v can cause random problems. When your battery fails it will be at the worst time. It's giving you a warning. Swap it out on your terms not it's terms.

    If you wait long enough the symptom may be the car won't start. Maybe it will start on the 3rd attempt.

    Or, you may approach the car in the dark. The interior lights don't come on. The handle doesn't work. Unlock the car with the key & enter a dark car. Try starting. Maybe it'll boot up the 3rd time. If so, drive straight to the garage to buy a battery. Yup, this is better. (Been here, done that when the 2nd battery failed in 6 weeks in the middle of November.)
     
    #9 JimN, Jan 3, 2012
  10. JetAgeHobo

    JetAgeHobo Junior Member

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    I'll definitely buy into the weak 12 V battery scenario. At that age only a matter of time, and I'm not encouraged by the voltage load readings. Will advise if this fixes the problem.
     
    #10 JetAgeHobo, Jan 4, 2012
  11. qbee42

    qbee42 My other car is a boat

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    It isn't that simple: good battery - works, bad battery - doesn't work. A marginal 12V battery in a Prius can produce all sorts of freakish behavior. Of the many electrical and electronic systems in the Prius, some start to malfunction before others as the 12V bus voltage is reduced. This can lead to spotty behavior, such as having the SKS shut down, but still be able to start the car via RFID.

    Tom
     
    #11 qbee42, Jan 4, 2012
  12. JetAgeHobo

    JetAgeHobo Junior Member

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    So took the car into the dealer to have it checked. They're testing showed 12V battery ok, one key fob dead, other so so. Sometime during the conversation with the service writer my wife pipes up that she washed one of the key fobs, would that have anything to do with it? Oookaaayyy, first I heard of this.

    Since the 12V battery 5 years old, had that replaced as well as the 2 key fob batteries. Not an inexpensive experience, but should be good for a few more years.

    One thing the service guy did mention, he says some people park their cars in the garage and have a tendency to hang the fobs on a hook next to the car, which keeps the car in sort of a 'ready' state and runs the battery down on the key fob and car quicker. Suggests keeping the key fobs away from the car when not using it.
     
    #12 JetAgeHobo, Jan 17, 2012
  13. andyprius

    andyprius Senior Member

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    The problem is, that when you are checking the battery, conditions are more favorable. Later in day, perhaps driven, suns up, etc. Very few people in thier right minds are going to go out in the cold at 5 AM and measure thier battery with a mult-meter. The SOC on any battery is going to be something less in colder temps.If your batteries are on the edge ( both ) then it is time to replace them. Normal length of service on the fob is >3 years and the 12V is >4 years, ( depending on conditions) Or you can do what the Japanese used to do, " Cover the battery with a blanket OR take it in the house every night" :cheer2:
     
    #13 andyprius, Jan 17, 2012
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