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Pre-collision system unavailable

Discussion in 'Gen 4 Prius Technical Discussion' started by Code, Apr 5, 2021.

  1. Code

    Code New Member

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    2016 Prius
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    Four
    New to priuschat, but I've been lurking a ton!

    Bought a used Prius, 2016 Four with 80k miles. Planned to run it in to the ground with a long commute and car-camping trips. My wife has a 2018 three that we love, also bought used, but CPO... mine is not.

    Anyway, I've had it 4 days, today I'm 50 miles in to my 60 mile drive home, come to a stop and the 'pre-collision system unavailable' message pops up. Ok, odd. Keep driving and realize that I can't use cruise control now either. Lane keeping screen says radar is available. Now the 'pre collision system unavailable' is displayed as soon as I start the car. along with the amber crashing cars symbol.

    Cleaned the emblem and windshield... now what? Just take it to a dealer to read the codes?

    Texas, 80 degrees, clear skies, clean roads. No collisions since I've owned it, but I haven't owned it long...
     
    #1 Code, Apr 5, 2021
  2. Code

    Code New Member

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    Location:
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    Vehicle:
    2016 Prius
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    Four
    Drove it to work today:

    1. Pre-collision system unavailable comes on as soon as the car is started.
    2. LDA works fine
    3. I took the under-hood cowling off and looked at the sensor behind the emblem, structurally it looks fine.


    Big time regrets on not getting a PPI or warranty. oof.

    How do I get this thread mod approved?
     
    #2 Code, Apr 6, 2021
  3. Code

    Code New Member

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    Well, like many in the stickied thread about this (didn't realize it was stickied, but I had read through it prior to posting) my issue magically went away on its own...
     
    #3 Code, Apr 7, 2021
  4. Code

    Code New Member

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    A thread all to myself. Might be useful to someone in the future: I've gone an additional 350miles since the original issue went away on its own and it hasn't returned.

    I pulled the DTCs using techstream and had a historical code in the Pre-Collision 2 ECU of U0235 "Lost communication with Cruise Control Front Distance Range Sensor."

    So there you go!
     
    #4 Code, Apr 8, 2021
  5. jerrymildred

    jerrymildred Senior Member

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    May I break into the monologue? :D

    I just spotted this. I wonder if there is or was a loose connection in the radar module. Or maybe some kind of debris in front of it that fell away when you took off the cover to check on it.
     
    #5 jerrymildred, Apr 9, 2021
    Code and alanclarkeau like this.
  6. Code

    Code New Member

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    You're welcome to join the monologue! Ha.

    That's a good theory, whatever it was hasn't come back so that's a relief!
     
    #6 Code, Apr 13, 2021
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  7. Engin3_Sussie!

    Engin3_Sussie! Junior Member

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    ----USA----
    It definitely sounds like the probem is debris. In any case you should post some photos so anyone who is an expert on this matter could give you a better opinion.
     
    #7 Engin3_Sussie!, Apr 18, 2021
  8. jerrymildred

    jerrymildred Senior Member

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    Why me? I'm not the one having a problem. And the one who had the problem isn't having it anymore. o_O
     
    #8 jerrymildred, Apr 19, 2021
    alanclarkeau and krmcg like this.
  9. Code

    Code New Member

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    Just post the pictures Jerry!


    Haha. If I have any more issues I'll be sure to add pictures. Just did a 500 mile round trip drive this last weekend to do some hiking and never had any issues. Even did a little 'off-roading' for about 2 mi down a forest road to reach our trailhead.
     
    #9 Code, Apr 19, 2021
    jerrymildred likes this.
  10. jerrymildred

    jerrymildred Senior Member

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    You want me to take apart my car to get a picture of the radar unit? :ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO:

    I refuse. :whistle: But then again, I had it apart for another reason about a year and a half ago. I had recently hit a bird and cracked the acrylic grill. So I actually happen to have a picture of the radar unit. Sort of. :D If you want a better picture, you can try Google or your toolbox. :)

    IMG_1639 cropped.jpg
     
    #10 jerrymildred, Apr 19, 2021
    Code and alanclarkeau like this.
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