Key Fob won’t lock after 12v Low Battery Message & Spare Key

Discussion in 'Gen 4 Prius Audio and Electronics' started by Newcomer, Sep 12, 2024.

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  1. Newcomer

    Newcomer New Member

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    My Prius 2018 Key fob won’t lock the car after getting a spare key. The 12v battery was low either in the process or right after the key guy was duplicating the keys. We jumped the small 12v battery and it started back up. Both keys fobs, old and new start the car alright but won’t lock or unlock the vehicle. I have to manually lock/unlock with the key.

    We did another key for another 2018 Prius, same model as the first, with no low battery message and everything works fine. Starts and locks.

    Key guys seems to think it’s because the 12v battery is low and driving it would solve the problem but I’ve kept it running on and off for about an hour now and still not locking.

    I also swapped out the batteries on the working Prius and it still won’t lock or unlock with the key fob. I put the “low” battery on the non problematic Prius and that key fob locked the car alright.

    Anyone seen this issue before and how can I solve it? Appreciate any help!
     
    #1 Newcomer, Sep 12, 2024
  2. bisco

    bisco cookie crumbler

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    i can't think of anything except that he should start the process all over again
     
    #2 bisco, Sep 13, 2024
    BiomedO1 likes this.
  3. BiomedO1

    BiomedO1 Senior Member

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    The locksmith needs to reprogram those keys again. Make sure your battery is charged up this time or hook a jump box to it - to ensure a constant 12VDC supply. The communications program protocols must've gotten corrupted because of the low battery.
    Since you had that fob apart, was the lock button nice and snappy or mushy. You may have a button/switch problem on the fob. You can jumper across the switch with a paper-clip or metal conductive tweezers, to test the button/switch issue..

    Hope this helps....
     
    #3 BiomedO1, Sep 14, 2024
    Brian1954 likes this.
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