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    Eug Swollen Member

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    The battery for one of my 2004 Prius key fobs is basically dead. I can't do the auto-door unlock with it anymore.

    Should I just let the service centre change the battery, or is it easy to do it yourself?

    What battery does it use?
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    aaf709 Ravenpaw of ThunderClan

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    It's something you can do yourself very easily. Take a look at http://www.vfaq.net/mods/keyfob.html to see pictures of the procedure. The battery is a CR2032, which can be found at a lot of places (like Radio Shack). At least on the 2005, the battery type is listed on the fob after you take the cover off.

    The hardest thing is finding the tiny Phillips screw driver, but you can get an eyeglass repair kit which should have one, or get a set from a hardware store.
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    seasalsa Active Member

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    Please refer to page 36 and 37 of your 2004 owners manual.
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    Eug Swollen Member

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    Thanks guys. It was a snap to do.

    So, is it true that you have to do it very quickly or the programming will be lost? There is no mention of that in the instructions.
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    JohnnieC New Member

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    For those as dumb as I was (or am I that i in a million): I almost broke the back cover, because I asumed I would pop it loose from the bottom up. As it is (once you push and hold the latch to the right) you simply push the back upward and it slips off the top!
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    donalmilligan089 Member

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    But if you haven't done it before ,the months or years have caused the back not to slip up easily and so one begins to think there is a different process. Been there done that
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    JLaPo New Member

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    I can't get the back off for the life of me.
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    inventor00 Orange County Prius Club

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    We had that problem with one fob- had spilled paint on it years ago.. (oops).

    Took it to our non-Toyota mechanic- were there for the other car and asked if he could get it off- he just popped it right off-

    the trick- he had RUBBER gloves on- which gave him a purchase, and of course he is very strong in the fingers....

    Also I showed him how with the other fob- so try it on the other fob also to get the idea.
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    direstraits71 Member

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    There is no programming in the fob that can be changed or lost. ie the codes present are burned into the circuitry. When you "program the fob" to your car, you are really programming the car to recognize the code present in the fob. This is why the fob works allowing the car to start even without a battery in the fob, when placed in the slot or positioned properly in the Gen 3 cars. The car activates the circuitry in the fob when the fob is in the proper position in the car, which allows the number in the fob to be read by the car which then starts.
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    Chasels You are what you eat

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    RatedN New Member

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    Pardon the bump back up, but I thought this might help someone who can't get their back cover off. I just had to change mine for the first time and thought it was stuck. For me, it helped to do in in this exact order:

    1) Start pushing (not too hard) the cover from the logo or the lip with your thumb.
    2) While pushing on the cover, slide the latch down slowly and watch for the cover to move. The release point for me was just a very slight distance away from the furthest position for the latch.

    Perhaps this is due to a production variation/irregularity for some fobs.

    It came off with very little force, so if yours isn't moving, you may not be doing it just right. Or you may have dropped your fob in molten lava at some point without knowing it and it melted together.
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    flipfloprunner New Member

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    Ok, I never post information, but thought this might help those with "weak" fingers like me. For the life of me, I could not get that cover off. Tried washing my hands, rubber gloves, tape... nada. Finally I used the small flat head screwdriver to poke into the small hole created when you slide the latch all the way back. I poked my screwdriver into that hole (which also held the latch open). I *gently* pushed up and the cover just slid off. It honestly felt like I applied less pressure than I was doing all that time with my thumb!! I guess the pressure I can apply with the screwdriver is all in the right direction (where as my thumbs were mostly mashing down (to create friction) and up to remove the cover. Try this if you have sissy fingers like me. :cool:
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    Pyrofer Junior Member

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    Ok, am I being VERY stupid or is there no way to stop the alarm when the keyfob is flat?
    Yes, the little hidden key worked to open the car but the alarm instantly started sounding and wouldnt stop!
    I tried putting the key in the ignition and that didnt stop it, hitting power didn't stop it either.
    I was rather panicked as it was late and people were staring so I didn't hang around to trouble shoot, I just closed and locked the car up. At which point it stopped happily.

    Now, I have a new battery on order, but in the few days till it arrives what am I meant to do???

    It's a 2006 Prius btw.
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    dbnelson62 New Member

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    There is also a good video on YouTube entitled "Prius Smart Key, Battery Replacement" that shows how to do it. (PriusChat won't let me include the URL, because I haven't made enough posts. Grrr!) This plus the writup listed earlier in this thread made it very easy for me to replace the battery.

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