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Red Triangle, no DTC, car drives fine?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Sarge, Oct 7, 2015.

  1. Sarge

    Sarge Senior Member

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    Hey guys,

    Looking to the community for some ideas.

    I have 365K KM (228k miles) on my 2006, and recently the dreaded red triangle came on, but without giving much hint as to why. The car continues to drive completely fine, and getting normal fuel economy.

    It first surfaced a few months ago immediately following a heavy rainstorm, and the triangle stayed on for a few hours, then went out on it's own.

    A few weeks later, again immediately after a HEAVY rainstorm, it came on again, but then went away after being parked in the dry for a few hours.

    About a month later, it came on again - this time without any rain - and then went away the next day.

    About 3 weeks ago it tried a new trick, where it would come on for 2 seconds, then go out for 2 seconds, then back on for 2 seconds and off, and so on. It did this for about 20 minutes as I drove to work one morning, and it coincided with the time a light misty rain had started. It again went away after a day or so. (This was especially annoying as it beeped each time, interrupting business phone calls I was trying to do while driving...)

    Last week, it came on again, this time for good. Did not seem related to the weather, and it has been on for about 10 days.

    I get the generic message about something wrong with the transmission parking gear and to park the car on a flat surface with parking brake on.

    The whole time, the car continues to drive completely normally, and getting regular fuel economy. (About 5L/100km). The check engine light has never come on, and my ScanGauge reports no codes.

    Today I took the car to my private Prius mechanic (who works almost exclusively on Prius and rebuilt my HV battery in 2013 (82K km ago), and his computer tells us nothing behind the scenes.

    Oil level, inverter, brake fluids all seem normal. The original 12v was replaced in Feb 2014 with Optima battery, which is about 60K km ago.

    I have a worn wheel bearing he will be replacing for me next weeks and the exhaust is making a bit more noise than normal, but otherwise the car is running like it always had, except for this message which keeps coming up - and it is coming up more frequently all the time (often I don't even have time to reverse into my parking space without the camera being cut off by this message - very annoying).

    Any suggestions on what could be triggering this?

    Thanks!

    Nobody has any suggestions? :(

    Hey everyone,

    Just to follow up, my awesome mechanic solved the problem!

    I had my car with him to replace a wheel bearing as well as investigate this problem, and after a couple hours of investigation, he found a wire related to the transmission control ECU which was not communicating and seemed to be the issue. He apparently bypassed it with another wire and problem fixed!

    He didn't have a picture of it, but he showed me the wiring diagram, the screwdriver in the pic points to the wire (blue) which was the problem.

    No idea how he found it, but glad he did!
     

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    Marty2go likes this.
  2. HGS

    HGS Member

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    That's great that he found it. With broken wires, it's anyone's guess what the problem is. I think that's why no one gave any ideas. That was a very strange symptom, and still driving fine.
     
  3. Sarge

    Sarge Senior Member

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    Indeed, and a bad wire was my first inclination, since everything seemed to be fine aside from this bloody triangle. I am so relieved he found it, for peace of mind. And I thought I would share the results in the remote chance this can help someone else in the future... :)

    Cheers!
     
  4. bisco

    bisco cookie crumbler

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    thanks, glad he found it, what a terrific mech! all the best.(y)
     
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  5. ChapmanF

    ChapmanF Senior Member

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    Just for future ref, any headline like "red triangle, no DTC" generally means you've been scanning for codes using a tool that doesn't see the Prius-specific DTCs. It doesn't mean there really aren't any (if the red triangle is on, there certainly are).

    A ScanGauge actually can see most Prius DTCs, but you first have to program it to do so, which is a little like texting the Gettysburg Address over a feature phone.

    The manual certainly shows DTCs related to communication problems among the ECUs, so the magic trick used by your mechanic may simply have been to connect a capable scan tool and then follow up on what was reported.

    -Chap
     
  6. Sarge

    Sarge Senior Member

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    Thanks Chap, and LOL about the comment about the Gettysburg Adddress, very true. :) I will be more careful in the terminology I use.

    I do have a lot of trust in my mechanic, as he is very much a friend whom has been working on my Prius for a few years, and rebuilt my HV battery several years ago, as he specializes in Prius. I was there when he first scanned the computer and it showed nothing out of the ordinary that would trigger this triangle. Not sure the name of his computer he uses, but it is a lot more advanced than my ScanGauge. ;-)

    I left the car with him for a few hours as I had him also replace a wheel bearing at the same time, and he told me he was able to determine this wire was the problem... I can't say how much his scan tool helped to finally locate the problem, but I know it did involve a good amount of testing...

    Anyway, just very glad it is resolved!
     
  7. goldfinger

    goldfinger Active Member

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    I have the exact same problem on my 2005. See thread /!\ Caution The transmission P lock mechanism is abnormal | PriusChat

    It hasn't happened for awhile, but every instance has been during or soon after wet driving. I wish your mechanic had taken a picture. Next time you're having work ask him to check his bypass and take a picture. That would make this a most helpful post. Thanks.
     
  8. Sarge

    Sarge Senior Member

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    Hey Goldfinger,

    I read your thread and it does indeed sound the same. :-/

    I did ask my mechanic if he could show me or if he took a picture, but unfortunately he did not take a picture, and he said accessing it is not easy as he had to take the dash apart on the passenger side where most of the ECU's and wiring harnesses are located... The best he could suggest was to show me the wiring diagram, which is what I took the picture of, above. :)

    However, if you are in Buffalo, then he's less than 2 hours away in Toronto if you want to make a short road trip. I can give you his name & number, just tell him Kevin sent you and you have the same problem. ;-)

    It would be even less expensive for you given the advantage you have with the exchange rate on the poor Canadian dollar these days. :)
     
  9. goldfinger

    goldfinger Active Member

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    Sarge, thanks.

    A resource like this should be shared. You should post your recommendation here Independent Prius Mechanics? | Page 2 | PriusChat.

    I'll probably leave it alone unless I have trouble getting inspected in March. Its very intermittent at this point and the car runs fine. That beeping can be annoying though. If I can get to this time next year and I'm still employed and the world hasn't ended I'll get a new car.