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Safety Sense braking: Do the brake lights turn on?

Discussion in 'Gen 5 Prius Main Forum' started by JNemin, Jul 24, 2023.

  1. JNemin

    JNemin Junior Member

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    I don't have a way of checking this, but I wonder of any of the automatic braking features turn on the rear stop lamps or center stop lamp?

    Or, are the rear stop lamps hardwired to only light up when the brake pedal is depressed?
     
  2. hill

    hill High Fiber Member

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    You could always get someone to follow you and record for yourself just to be sure, or take a total strangers' word on it
    ;)
    .
     
  3. ESh

    ESh New Member

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    The brake lights turn on whenever you brake by pressing the brake pedal, by decreasing the speed on RCC, waiting on read light when HOLD is activated...
     
  4. tovli

    tovli 2023 Prius Prime replaced 09 Prius

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    The manual suggests the rear brake lights are activated when strong regenerative engine braking is occurring
     
    JoeBlack likes this.
  5. daisy555

    daisy555 Senior Member

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    Wouldn’t the brake lights have to come on when automatic braking features are activated. Otherwise it would be a major safety hazard for those driving behind you. Please let us know what you find out.
     
    #5 daisy555, Jul 28, 2023
    Last edited: Jul 28, 2023
  6. BiomedO1

    BiomedO1 Senior Member

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    FWIW; my understanding of the system. No brake lamps if the system zeros out the accelerator pedal (ie. coasting). Rear brake lamps light up if ABS pump activates to apply brake force (actual braking). I haven't had a chance to test this. Just my interpretation of the system as printed in the manual.
     
  7. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    It's simpler than it seems.

    If any of the safety systems need to use the brakes to slow or stop the car, then the stop lamps illuminate.

    The safety systems don't know anything about the regen vs. hydraulic brakes- there's no need. They just ask for more braking or less braking and let the brake controller worry about the details.
     
  8. Jim Call

    Jim Call Active Member

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    Yep, agree with your assessment and is actually what happens from observation with my XLE.
     
  9. fuzzy1

    fuzzy1 Senior Member

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    Is the specific to your Prime manual, or is it in the non-Prime manual too?
     
  10. BiomedO1

    BiomedO1 Senior Member

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    I would assume it's the same system; otherwise Toyota would have to resubmit test results instead of telling them it's the same safety system; only in a different model.

    Engineering and safety testing x2 for effectively similar cars would have to be submitted to the NTSB for certification if they were materially different systems.
     
  11. tovli

    tovli 2023 Prius Prime replaced 09 Prius

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    Probably this only applies to the Regen-Boost mode (pg 261):

    Regen_StopLights.jpg
     
  12. tovli

    tovli 2023 Prius Prime replaced 09 Prius

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    Pg 331 Dynamic Radar Cruise Control - "preceding vehicle driving slower than the set speed is detected...the stop lights will come on at this time"

    DRCC stoplights.jpg
     
  13. ColoradoBoo

    ColoradoBoo Senior Member

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    Good to know!

    On the same line, does anybody know the rules for the "place hands on steering wheel" warning we, sometimes get? I was driving a friend around and he wanted to see it....but no matter how long I left my hands off the steering wheel, the stupid thing wouldn't put out the warning...making me out to be a big liar!!

    Smart a** Toyotas!!! ;-)
     
  14. fuzzy1

    fuzzy1 Senior Member

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    There are enough differences, with the Prime having greater electrical capacity than the non-Prime, that I would not make that same assumption.

    At least for my Gen3 non-Plug-in, I'm not aware that regen or engine braking will ever light up the brake lights. It isn't strong enough to need to, it can't provide as much braking as downshifts in manual transmission vehicles that also don't activate the brake lights. And I'm not aware of Gen4 non-Primes doing any different.

    Driver assist features that activate the hydraulic friction brakes do need to light up the brake lights.
     
    #14 fuzzy1, Jul 29, 2023
    Last edited: Jul 29, 2023