Dynamic Cruise Control Interference?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by RMulligan, Mar 5, 2012.

  1. RMulligan

    RMulligan Junior Member

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    I was driving on the 405 Freeway (in Los Angeles) with the DCC operating normally. The display showed one bar to the car in front. All of a sudden the display was briefly replaced with a large white rectangle. The white rectangle flashed a few more times for the next 30 seconds. Then everything was back to normal. When the white rectangle was displayed, the car decelerated. Then it accelerated when the DCC display returned.

    Does this sound like an internal DCC problem or possibly an external radar interference problem? The problem occurred at the intersection of the 710 Freeway in Long Beach. I drove by the intersection later that night and no problems. I was in the carpool lane both ways and the center divider is a concrete K-rail design.

    Thanks for your help,

    Rich
     
  2. ImeanGreen

    ImeanGreen Prius v Five BP Brigade #236

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    Looks to be operating normally. Seems to me that you choose the closest distance. My guess is that, when the setting reached it's pre collison distance, it had to decelerate when you got too close to the car in front of you and resumed to it's normal cruising speed once the car in front of you got out of the way. Here's a video of how it works.

    2010 Toyota Prius: Dynamic Radar Cruise Control - YouTube
     
  3. KK6PD

    KK6PD _ . _ . / _ _ . _

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    Although I do not own the ATP option, my loss, Yes it could conceivably be RADAR interference. What you need to do is repeat the failure with consistency. Radar signals that strong are usually from fixed sites. Drive your route several times, see what happens. If you can repeat the situation, you can at least expect it when you are in that particular area!
    What you describe is loss of DCC lock, followed by the reacquisition data box being displayed, data collected, targeting acquired, DCC Engaged again. I would expect loss of power as well, as cruise control was disengaged also!
    I might even suspect a CHP Mobile radar, at close range, their signal could easily overload the front end or the DCC ranging receiver! I have a detector in my car, and they are all over the place!
    I need to find out more info on things like what frequency DCC operates at for one, range and power levels would be nice to know also! Beam pattern, receiver window look angle..
     
  4. mad-dog-one

    mad-dog-one Prius Enthusiast

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    I have encountered a few PCS stage 1 warnings (not DRCC) in locations were there was a dip or rise in the road and the highway surface changes from asphalt to concrete. Alhough the brakes were not applied, I believe the DRCC was released and that the brake sensitivity was enhanced. I may be wrong, but believe the flashing triangle is PCS, not DRCC. It all happens so fast that it is difficult to remember everything.
     
  5. 32kcolors

    32kcolors Senior Member

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    Normal operation during hard deceleration. Sounds like something crossed your path or it detected a slow moving car.
     
  6. tumbleweed

    tumbleweed Senior Member

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    PC member Thai reported a similar problem a year or so ago. He had repeat occurrences on the same flat stretch of highway and even posted a video of it. As I remember he was never able to find the cause. I think most of us assumed it was outside interference.

    That's the only other case I can remember that was posted on this site.

    Edit: Here is the thread I was referring to but for some reason Thai has removed most of his posts and the video? Anyway you can an idea of what the problem was by reading the replies.
    http://priuschat.com/forums/gen-iii...e-troubleshooting/94549-drcc-malfunction.html
     
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  7. RMulligan

    RMulligan Junior Member

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    Tom, thanks for the link to the DRCC Malfunction thread. That helps a lot. I tried searching for DCC instead of DRCC - oh well.

    I've seen the PCS warning symbol and audio before - so it was not the PCS.

    I've see the DRCC warning when a car in front of me is decelerating to fast for the DRCC to slow down - so it was not that (there was no car icon on top of the single bar).

    Based on the replies to both threads I think it must have been interference from a radar source (there is a Hughes/Raytheon facility at the intersection of the two freeways). When the DRCC is confused, it must automatically go into a "safe mode" that disengages the accelerator. Since the interference was brief, the car started accelerating again when the white box was cleared from the MFD. So the DRCC must have reset itself and re-engaged the last programed setting. Since the white box appeared one or two more times in quick succession, I guess I might have passed through side lobes (?) of the transmitter.

    I just hope I don't experience this again. It would be good to know for sure.

    Thanks everyone for your help.
     
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