Key fob or lock cylinder

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusDad502, Jul 3, 2026 at 9:19 PM.

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  1. PriusDad502

    PriusDad502 New Member

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    My 09 Prius has a weird issue. It self locks and unlocks when we’re sitting in the car or even near by.

    Sometimes it won’t respond to unlocking or when I press lock it does a consistent beep tone until I unlock it.

    I don’t know if it’s the Fob messing up or the lock cylinder

    everything else works fine starting wise. So does the fob slot.


    I’m clueless and don’t want to buy a new fob
     
    #1 PriusDad502, Jul 3, 2026 at 9:19 PM
  2. bisco

    bisco cookie crumbler

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    it's not the lock.
    do you have a second fob?
    does it have a fresh battery from a quality source?
    has the 12 volt been load tested?
    if you eliminate the batteries as the issue, it has to be a bad/sticky fob (try cleaning it inside with isopropyl alcohol) and make sure none of the buttons are stuck.
    then it could be the door switch, unlikely, or the ecu.
     
    #2 bisco, Jul 4, 2026 at 2:25 PM
  3. PriusCamper

    PriusCamper Senior Member

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    Your FOB is corroded and switch is sending signals even though you haven't pushed a button. Take it apart and clean and inspect... Use circuit board cleaner on the circuit board and if you're lucky that will fix it. If not, you'll need to replace it.
     
    #3 PriusCamper, Jul 4, 2026 at 3:14 PM
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