1. Attachments are working again! Check out this thread for more details and to report any other bugs.

When Radar Cruise Control slows car, do brake lights illuminate?

Discussion in 'Gen 3 Prius Main Forum' started by Coastie, Oct 22, 2009.

  1. Coastie

    Coastie New Member

    Joined:
    Jun 29, 2009
    9
    2
    0
    Location:
    El Dorado Hills, Ca
    Vehicle:
    2010 Prius
    Model:
    V
    This question came to me as I was bucking stop and go traffic in the Bay Area. Seems like it would be nice if the guy behind me had a warning that I was slowing.
     
  2. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,075
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    I would suspect not. When you lift your foot from the gas, the brake lights to not illuminate.

    Tom
     
  3. PRPrius

    PRPrius Active Member

    Joined:
    Jul 5, 2004
    327
    198
    2
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    that is a good questions! I know for a fact that Mercedes activates the brake lights when the vehicle automatically applies the brakes. I think the Prius should definetly activate the brake lights if the car uses the brakes to slow down. Granted, most of the time the prius will most likely use the regenerative braking mode.
     
  4. garygid

    garygid Senior Member - Blizzard Pearl

    Joined:
    Aug 23, 2009
    379
    23
    0
    Location:
    Orange County, CA
    Vehicle:
    2010 Prius
    Model:
    III
    If the brake pedal is depressed just a little bit (about 1/4 to 1/2 inch), my P-III + Nav turns on the brake lights.

    If the car is slowing any substantial amount, the brake lights really should come on.
    To test, loosly tape a small strip of paper over part of the 3rd (high) brake light and down over the lower window, and you should be able to see a red glow on the paper strip (in the rear-view mirror) when and if the light comes on.
     
  5. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,075
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    Regenerative braking is the same as any other braking, except for the small amount used to simulate engine drag. I agree that the issue is whether the car slows due to braking or simply removing power. If it is removing power, then no brake lights are needed. If it applies the brakes, then the lights should come on.

    Tom
     
  6. WmDaniel

    WmDaniel New Member

    Joined:
    Sep 14, 2009
    2
    0
    0
    Location:
    California, USA
    Vehicle:
    2010 Prius
    Model:
    V
    This was a concern of mine as well. The break lights do not illuminate in this situation. Think about it like downshifting a standard transmission, using the engine to slow the car. In that case the car slows without activating the break lights.

    Daniel
     
  7. SFBayAreaPrius

    SFBayAreaPrius New Member

    Joined:
    Jan 26, 2009
    10
    0
    0
    Location:
    San Jose, CA
    When the laser or radar cruise on any Toyota slows the car, the brake lights do go on.
     
  8. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    45,024
    16,242
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    how hard does it have to slow down before the brake lights come on? The same as if you were to drive??

    Sometimes the DRCC appear to just coast so I presume under those conditions, the lights won't come on. It's only when it starts to apply the brakes, then the brakelights will come on. Am I right?
     
  9. swerthei

    swerthei Junior Member

    Joined:
    Jul 29, 2009
    15
    11
    0
    Location:
    California
    Vehicle:
    2010 Prius
    Model:
    V
    It depends. The RCC has two different methods it can use to slow down the car. It can let up on the throttle, for gentle deceleration, or apply the brakes when it needs to decelerate harder, like when you're coming up fast on slower traffic. The RCC decides which to use based on how quickly it thinks you need to slow down. When it only lets up on the throttle, your brake lights don't come on - same as when you take your foot off the gas. When it applies the brakes, your brake lights do come on, just like when you apply the brakes yourself.
     
  10. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,075
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    Does it have a mode to simulate an elderly driver, where it rides the brakes and drives with the left turn signal continuously flashing?

    Tom
     
  11. KFriesen

    KFriesen Junior Member

    Joined:
    Aug 12, 2019
    6
    1
    0
    Location:
    Penticton BC Canada
    Vehicle:
    2020 Prius Prime
    Model:
    Plug-in Base
    I was driving back from Spokane today on my first ‘road trip’. I thoroughly enjoyed the drive using the cruise technology on my new prime. The same question came to my mind as several times the car braked fairly fast. Are the brake lights coming on to warn those behind me that I am stopping faster than normal... What I really liked was how the cruise worked in the mountains. In the past you just couldn’t use cruise at all on curvy roads. I noticed that my car would anticipate the sharp corners ahead of time and slow the vehicle before getting to the corner. Very impressive! I found it would bring me to a complete stop a number of times and actually start moving with the traffic as it started up. Sometimes I just needed to tap the accelerator to get it going again! Amazing!