2006 Prius both key fobs not working

Discussion in 'Gen 2 Prius Main Forum' started by RSP, Aug 1, 2021.

  1. RSP

    RSP New Member

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    Hello friends,
    I purchased 2006 Prius recently. First time owning a Prius.
    I had a low battery in one of the key fobs. So I replaced it with new one. At the same time, I also replaced the battery on the other key fob as well.
    Now none of these key fobs are starting the car.
    The car's battery is good. 12V battery was also showing full green on the display before I decided to replace key fob batteries after reaching home.
    As of now, I get no lights on the dashboard - not even door open/close indicator.
    I tried resetting the Key button and also what I read somewhere as a 'chicken dance'.
    Nothing.
    Also tried inserting the key fob in the slot and pressing the power button. The led on the power button glows green. Park button led is green. But nothing on the dashboard.
    If I press open or close button on the keyfob I can hear a small beep coming from the car.
    When I press open button when sitting inside the car, I see some fluttering of left green arrow for 2 seconds.

    As I mentioned, I am very new to Prius. I searched the forum for similar problems and did bunch of fiddling around as some of you recommended - all from inside the car.

    I would appreciate any pointers that you may provide.

    Please, please help!

    RSP
     
  2. ToyotaGal

    ToyotaGal Member

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    I recently changed my battery as well. I had no issues. Are you sure you put in the new batteries? Did they go in the right way? Take them out and test them to make sure you got good ones and they are the right ones.
     
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    Do you have a digital voltmeter to be able to measure the voltage level of the 12V battery? What you describe sounds like the 12V could be very weak. The Prius is a car-shaped computer that you can drive around in (when it works). The computers in the car get all their electrical power from the 12V until everything "boots up" (when you press the power button) - then the high voltage battery (and the gasoline engine) take over supplying power.

    With everything on the car turned off, the 12V should ideally read 12.6 to 12.8V if it is in good condition and is fully charged. If it's below 12.0 then it should be charged and tested (or replaced if it's more than 4-5 years old or it fails a load test).

    FYI the "battery gauge" in the center screen shows the approximate useful capacity of the high voltage battery.

    Posted via the PriusChat mobile app.
     
  4. RSP

    RSP New Member

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    Thank you ToyotaGal for the response. These are the brand new, freshly purchased - Energizer CR2032 batteries that I put in the key fob. The batteries are inserted correctly. Red LED on the key fob glows when I press either of Open or Close buttons on the keyfob.
     
    ToyotaGal likes this.
  5. RSP

    RSP New Member

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    Thank you mr_guy_mann for your response.

    The 12V battery is relatively new. I had been driving the car for a few days and the battery gauge on the center screen always used to show 12V battery charging after a few minutes of driving to a green color bars (filling almost 90%). The 12V battery was showing up as almost 90% filled with Green color on the battery gauge on the center screen before I parked & switched off the car- and then - immediately thereafter I replaced the batteries in both the key fobs. Right thereafter, I went on to start the car just to make sure that the newly inserted batteries work. Unfortunately, both the keyfobs stopped working - since I replaced batteries in both of them at the same time.
    Thereafter, I bought another fresh pair of CR2032 batteries from the store - and then replaced them in the keyfobs.
    No luck.
    None of the keyfobs are working.
    The LED on the keyfob does glow to red when I click on the open or close button.
     
  6. dolj

    dolj Senior Member

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    Hello and welcome to Prius Chat.
    Did you refit one of the fobs with one of the old batteries?
    I read a post that claimed that a new battery had too high of a voltage and the fob did not work. I think they said that the voltage was above 3.4 V and when they discharged the new battery to under 3.4 V the fob worked again. YMMV.
    That graphic on the MFD shows the 40% to 80% range of the hybrid vehicle (HV) battery which is the big battery (aka traction battery) that sits behind the rear seat. The graphic has nothing to do with the 12 V battery that is in the right rear of the car.

    You need to measure the 12 V battery with a voltmeter at the front jump point (easier to get to) under the hood or at the battery terminals on the battery in the rear (more work to get to).

    Even though you say the battery is relatively new, it does not mean it can't be low on charge. Let us know what the voltage is when
    1. The car is off. Measure and record the voltage.
    2. With the car still off switch the headlight on high beam and immediately measure and record the voltage to which it drops.
    3. Leaving the car off with the headlights on high beam (from 2 above) measure and record the voltage after 5 minutes (before turning the lights off).
    4. Turn the lights off.
    If the voltage drops below 9.5 V before the 5 minutes is up, stop the test and replace the battery. Otherwise report the 3 voltages from above.
     
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