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Possible issue with classic cruise control

Discussion in 'Model S: Driving Dynamics' started by Carguy949, Aug 10, 2017.

  1. Carguy949

    Carguy949 Member

    Jan 2, 2014
    Southern California
    I've noticed an anomaly with my classic cruise control and I'm wondering if anyone else has experienced it. If I'm making a gradual transition to a lower speed zone, I'll reduce speed in a number of steps. For example, if I have it set to 75mph and I'm working my way down gradually, I'll press the stalk down a little for minus 1mph and past the "click" for minus 5mph. I've noticed that after a few (4? 5?) such requests, and allowing it to finish adjusting before pressing down again, it will ignore any further requests to reduce speed. It's as if there's a limit to how far it will let you adjust. Even if I give it a little more time, pressing down on the stalk does not reduce speed any further. At that point, I just touch the brake to cancel it.

    I had the car in for service yesterday and mentioned that, but I'm not sure they fully understood what I was describing because they just said they drove the car and the cruise control is working normally. Is this normal behavior?
  2. Snowstorm

    Snowstorm Member

    Dec 8, 2016
    Ontario Canada
    I haven't seen this issue. Though I only lower my speed maybe 10-15 units. How do you get classic cruise control? Doesn't it always TACC?
  3. swaltner

    swaltner Member

    Oct 13, 2012
    Kansas, USA
    You get dumb or classic cruise control if you don't have the autopilot option. Once you purchase autopilot, you get switched to TACC.

    While I don't know if that's normal behavior, for the OP, I'd suggest recording a video showing the behavior or have them ride along with you. That's something I can see a service technician misinterpreting what you're trying to explain.
  4. Musterion

    Musterion 18h 03m 37s −24° 23′ 12″

    Jan 10, 2013
    I haven't seen this but will check it out if you can clarify the parameters: are you saying you only see this when reducing speed? And does it happen when you only do multiple 1-mph corrections or it needs to involve the 5-mph correction? If the latter, I am wondering if any of your tests take you below the minimum speed requirement for classic cruise. In my original software (v4/v5) this was set at 17mph but this limit may have been raised in subsequent software versions. (TACC as I understand it from new manuals has a lower speed limit, like 5 mph). Unfortunately the newer manuals no longer even mention the original cruise control specs and operating parameters.
  5. David99

    David99 Active Member

    Jan 31, 2014
    Brea, Orange County
    Try keeping pressing it down. As long as you hold it down it will reduce speed. I noticed it will ignore push downs if the difference between speed and desired speed is too much. Say you go 75 and press it down several times. The little marker goes to 55 (or something like that) but it will ignore your request to set it lower until the actual speed has somewhat caught up.

    There is a lower speed limit, but I believe it's somewhere around 20/25 mph.
  6. Nick B

    Nick B Member

    Sep 15, 2016
    Not sure this would really considered as an issue... if you're going at 75 mph and you reduce speed to 35 or 40 shouldn't you be simply disabling the cruise control?
  7. hacer

    hacer Member

    Apr 13, 2016
    Clarksville, MD
    It does have a minimum of 20 MPH, you can't set it below that, although TACC will operate below that if the car ahead is going less than 20.

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