Adaptive cruise control / safety sense issue

Discussion in 'Prime Main Forum (2017-Current)' started by xvs, Jul 6, 2017.

  1. xvs

    xvs Member

    Joined:
    Aug 29, 2009
    88
    30
    0
    Location:
    san francisco
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    I was driving in slow traffic on the highway a couple of days ago. Adaptive cruise control was set to nearest distance and 65 MPH. Traffic was moving about 45MPH.

    The car in front of me changed lanes, and cruise control seemed to switch off with no error messages, beeps or other warnings at all. The car stopped braking and seemed as if it was about to hit the car immediately in front of me. I know that it would accelerate to close the gap, but there was almost no gap because it was nearly bumper-to-bumper and traffic was slowing down at the time.

    Safety Sense did not activate, and there was no warning of any kind. Luckily my foot was hovering over the brake and I was able to stop in time, but it was very worrying.

    Has anyone else seen this behavior?

    Something similar happens a lot but with warnings: the car in front will change lanes, there's a fairly large gap, a warning appears "no preceding car" and cruise control turns off. Wth? Why would it do that? It's supposed to work even if there is no preceding car, and then just go at the speed that was set, isn't it?

    This needs to be fixed.
     
  2. xray22

    xray22 Junior Member

    Joined:
    Oct 8, 2009
    31
    13
    0
    Location:
    Vanouver, WA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    That is scary. All these bugs need to be brought to the attention of Toyota. I would call my dealer's service department as well as calling Toyota direct. If nobody does this, these things will never be fixed. It probably requires a simple firmware update.
     
  3. Washingtonian

    Washingtonian Senior Member

    Joined:
    May 26, 2017
    591
    530
    0
    Location:
    Western Washington
    Vehicle:
    2017 Prius Prime
    Model:
    Plug-in Advanced
    Are you talking about the dynamic cruise control on the Prime? Your avatar shows a 2010 Prius is why I asked.
     
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    24,288
    13,814
    0
    Location:
    Huntsville AL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    If at any time the speed is below 28 mph, the adaptive cruise control will shutoff if the car in front changes lane. But I always expect to take over from adaptive cruise control in either or Prime or BMW i3. They are 90% OK but not perfect.

    Bob Wilson
     
  5. Krzysiek_KTA

    Krzysiek_KTA Active Member

    Joined:
    Mar 28, 2017
    153
    121
    0
    Location:
    Houston
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    I tend to agree with one reservation: DRCC works OK only in Toyota presumed conditions. I wish there was another method to hold the car still at stop/red light other than engaging DRCC behind preceding car. DRCC works on HWY in steady predictable traffic ONLY. Other than that one's foot needs to hoover over the brake or acc. pedal depending on conditions.
    Over my experience with Prime I am going to abandon DRCC other than when cruising on hwy.
    We can wish for some decent DRCC, but for now we are left to stick to Toyota's recommendations.
     
  6. CaliforniaPrius

    CaliforniaPrius Active Member

    Joined:
    Oct 29, 2012
    313
    199
    0
    Location:
    Alameda, California
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    Here is your problem. When the traffic slows down you need to adapt the set speed manually.

    It happened to me several times, exactly the same scenario which the car in front of suddenly changes lane. The idea is that it looks to me the car wants to accelerate to satisfy the set speed first, THEN consider if the gap in between gets too close. If the speed difference between your set speed and the actual traffic is too big, it is a disaster waiting to happen.

    The way to solve this potentially dangerous scenario is to manually adjust your set speed to match the traffic. Whenever you see most cars in front of you have their brake lights on, it is time to adjust your cruise control speed. It happens frequently when highway branches off or merges in.

     
    #6 CaliforniaPrius, Jul 6, 2017
    Last edited: Jul 6, 2017
  7. xvs

    xvs Member

    Joined:
    Aug 29, 2009
    88
    30
    0
    Location:
    san francisco
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    Yes, I now have a Prius Prime... have to update that.

     
  8. priuscatprimeguy

    priuscatprimeguy Senior Member

    Joined:
    Nov 1, 2016
    2,730
    2,634
    0
    Location:
    Farmington Hills, Michigan
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    take your time, we got all night:p
     
  9. xvs

    xvs Member

    Joined:
    Aug 29, 2009
    88
    30
    0
    Location:
    san francisco
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    If so, they really need to fix this and supply a patch. It shouldn't be doing that. The entire point of adaptive cruise control that goes down to zero is to deal with variable speed traffic!

     
  10. Sam Spade

    Sam Spade Senior Member

    Joined:
    Dec 3, 2016
    2,036
    1,011
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    The entire point of adaptive "cruise control" is NOT for use in variable speed, stop and go traffic.
    Dealing with traffic "slow downs" is not cruising.

    As was pointed out, if your speed set point is more than 20 MPH above the current speed, I would expect the cruise to dis-engage.

    I think you are using the system in a manner for which it was NOT designed.......and expecting them to re-engineer it to work the way you want it is......unrealistic.
     
  11. fotomoto

    fotomoto Senior Member

    Joined:
    Apr 22, 2009
    5,336
    3,567
    0
    Location:
    So. Texas
    Vehicle:
    Other Hybrid
    It's been my experience that these are a fail-safe emergency braking system design to hopefully avoid a collision but if not mitigate damage. They are NOT auto-pilot type systems. It will be a few more years for those to enter widespread adoption.

    I used a large empty TV box in an empty parking lot to test auto-braking. 2 out of 5 times it hit (barely) the box. Why? It was far beyond the systems capability to factor in loose gravel and the ABS kicking in thus making the stopping distance longer.
     
    Andyprius1 and priuscatprimeguy like this.
  12. Washingtonian

    Washingtonian Senior Member

    Joined:
    May 26, 2017
    591
    530
    0
    Location:
    Western Washington
    Vehicle:
    2017 Prius Prime
    Model:
    Plug-in Advanced
    Interesting to know that the box trick worked.
     
    priuscatprimeguy likes this.
  13. xvs

    xvs Member

    Joined:
    Aug 29, 2009
    88
    30
    0
    Location:
    san francisco
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    That used to be the case for the older adaptive cruise controls that cut out under 20MPH or so, but this one specifically goes down to 0MPH and is specifically designed to work in stop-and-go traffic.
     
  14. joachimz

    joachimz Senior Member

    Joined:
    Jan 21, 2012
    445
    600
    17
    Location:
    SoCal
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    manual pg 393:
    DRCC warnings.jpg
     
    alexcue, fuzzy1, uber2016 and 2 others like this.
  15. Prius from Dad

    Prius from Dad Senior Member

    Joined:
    Oct 5, 2012
    724
    1,115
    0
    Location:
    Toms River, NJ USA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    uber2016 and joachimz like this.
  16. joachimz

    joachimz Senior Member

    Joined:
    Jan 21, 2012
    445
    600
    17
    Location:
    SoCal
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    and i am not disputing that it does work, tried it myself in stop and go, jerky acceleration and heavy braking, it is not for me in that situation but ymmv.
    Clearly Toyota is covering their rear, get in an accident during such situation and sue Toyota for it ... good luck, didn't you read the manual???
    I would encourage everyone to read section 5.5 of the manual, while it is over 100 pages, pay extra attention to the "Warning" sections, nice pink heading, bet those were written by motor enthusiast lawyers :barefoot::rolleyes:
     
    uber2016 and Prius from Dad like this.
  17. Prius from Dad

    Prius from Dad Senior Member

    Joined:
    Oct 5, 2012
    724
    1,115
    0
    Location:
    Toms River, NJ USA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    That is exactly why I don't use it for stop and go traffic.
     
    uber2016 and joachimz like this.
  18. joachimz

    joachimz Senior Member

    Joined:
    Jan 21, 2012
    445
    600
    17
    Location:
    SoCal
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    Thread hijack alert: catching up on you on fuel-ups ... 8th fuel up yesterday, 8.4 gas for 1150 miles or so, 135.9 according to Fuelly and lifetime now at 103.1 ... but it's going down from now on as my Chargepoint is expiring tomorrow so no more charging at work for some time ...
     
    Prius from Dad likes this.
  19. Prius from Dad

    Prius from Dad Senior Member

    Joined:
    Oct 5, 2012
    724
    1,115
    0
    Location:
    Toms River, NJ USA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    (y)(y)...:( Can you charge at home? I wish I could charge at work. Then I would have the "problems" some of these guys have with worrying about stale fuel. :ROFLMAO:
     
  20. joachimz

    joachimz Senior Member

    Joined:
    Jan 21, 2012
    445
    600
    17
    Location:
    SoCal
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    yea, i typically charge over night, and sometimes during the day on weekends if needed. I wish i had the "stale fuel" problem but with a 100 mile roundtrip commute - not happening with the Prime, but that's fine, loving that car, still :p:love:
     
Loading...