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Brake Light Switch, what is the failure rate?

Discussion in 'Gen 2 Prius Audio and Electronics' started by gen 2 owner, Jun 27, 2019.

  1. gen 2 owner

    gen 2 owner Junior Member

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    Hello.
    My car Is still hard to start most of the time.
    I have charged the aux. battery twice now and still it acts up.
    I found that with trial and error if I place my foot on the brake pedal with a different angle and force and hold it there down, the car will start flawlessly.
    If I let go of the brake pedal and push it again, say lighter and in a different position the car will not start, ie power led goes from off to green to orange, but ready does not light on dash.
    I'am now going to see if the distance from the branke light switch and the pedal is correct, if correct, I think I will buy a new switch.
    I also will get a friend to check my brake lights and see if they are intermittent, the last time I checked the cruise control operation, it works okay.
    Do these brake light switches have a high failure rate, my car is a 2005.

    Any info would be appreciated.

    Thank you.
     
    #1 gen 2 owner, Jun 27, 2019
  2. jerrymildred

    jerrymildred Senior Member

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    I've never heard of one failing, but any switch can fail. Years ago, I had to adjust one. I think you're on the right track.
     
    #2 jerrymildred, Jun 28, 2019
  3. JC91006

    JC91006 Senior Member

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    I've had a brake light switch fail on a 2006. But when it failed, I got a code.

    The switches are fairly cheap, especially on the used market (I might even have one to sell you). Just make sure you buy oem Toyota part, not an aftermarket. Installing it can be a bit difficult cause there's not much room to work under the dash.
     
    #3 JC91006, Jun 28, 2019
  4. bisco

    bisco cookie crumbler

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    try adjusting it. failure rate has nothing to do with your problem.

    back up to a wall in the evening. its pretty easy to see if your brake lights are working correctly
     
    #4 bisco, Jun 28, 2019
  5. gen 2 owner

    gen 2 owner Junior Member

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    Thank you for all the info.
    I will check the switch this weekend.
    Solution will follow.
     
    #5 gen 2 owner, Jun 29, 2019
  6. gen 2 owner

    gen 2 owner Junior Member

    Joined:
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    2005 Prius
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    Two
    Hello.
    I removed the stop lamp switch and tested it with an ohmmeter.
    I found the switch that turns on the brake lights to be okay.
    The other part of the switch was always open, it looks like it switches the ignition 12v thru it.
    I took it apart and fixed it.
    Now when the brake pedal is pressed the brake lights turn on and the ignition switch turns off.
    When the brake pedal is not pressed the lights turn off and the ignition switch turns on.
    The Bentley repair book confirms this in the wiring diagram, one switch closed while the other open.
    The Toyota manual shows 3 possible areas of trouble:
    1. stop lamp switch., filxed
    2. power source control ecu.
    3. wiring harness

    Has anyone had a similar problem.
    I think with all the bumps the car takes in it's lifetime that a bad connection would be the next culprit.
    Has anyone had to fix cracked solder connections on the power source ecu or a bad wiring harness to the ecu.
    I tried to start the car approx. 20 times and it started approx. 4 times.
    When it did start, ready on dash, when the power was turned off, it would not go again.

    Any help would be appreciated.

    Thanks.
     
    #6 gen 2 owner, Jul 4, 2019
  7. bisco

    bisco cookie crumbler

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    is it possible rodents chewed on the wiring harness?
     
    #7 bisco, Jul 7, 2019
  8. 3prongpaul

    3prongpaul Hybrid Shop Owner, worked on 100's of Prius's

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    The stop light switches rarely fail, but I have seen a couple fail over the years. There are 4 pins, 2 are for the brake light circuit (which are important when you power on the car). If your brake lights don't come on when you press the brake pedal, there is no way your Smartkey Prius is gonna start. The other two pins are for the cruise control circuit.

    OP, are you sure it's not something else? weak 12V battery, poor cable connection on 12V?, weak fob battery? Is security light off (not flashing) when you enter the car?
    (put fob in dash slot to eliminate fob battery as an issue).
     
    #8 3prongpaul, Jul 11, 2019
    Last edited: Jul 11, 2019
  9. abcsoup53

    abcsoup53 Junior Member

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    Did you ever fix your issue?
     
    #9 abcsoup53, Jun 15, 2022
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