Red Triangle on Start Up that goes away 12v test good

Discussion in 'Gen 2 Prius Technical Discussion' started by Hx214, Jul 11, 2019.

  1. Hx214

    Hx214 New Member

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    Looking for advice on this.

    I’m getting ready to take a 8 hour road trip with my wife and kids. Had the Prius in my shop giving it the once over before we leave in a couple days. Everything looks good.

    Drive it on a two hour one way trip and back, runs great.

    We leave for the big trip in two days, and yesterday I get in to leave and when I start it, the red triangle pops up on the dash.

    I lean forward and put my head on the steering wheel in defeat.... pick my head up and it’s gone....

    Turn the car off and restart and no Triangle.

    Got my scanner out and no codes logged. No pending codes.

    Drive an hour to my parents with no issues, no lights. After visiting for a few hours get back in and Triangle pops up but goes away so fast I can’t even get my scanner pulled in to catch it. Scan again... no codes.

    Drive an hour home. No issues. Park it.

    Go out this morning, to check it, get the Triangle but this time I see the icon for the headlight leveling system, but then everything goes away...

    I go through the procedure to test my battery thinking it’s done. Everything is in spec. (Well... I’m getting 12.3 on ACC mode and I think it’s suppose to be 12.4) Has 12v at load and sits at 14v when charging.

    When I got the car from my buddy he had the car for a year and it had a yellow optima when he bought it. I’ve had it about 8 months with the same battery, so I know it’s almost two years old at the very least. (Can’t find a date on it)

    So here is where I need some advice. If I wasn’t going on a trip I’d let it play out and see if it gets worse. My gut says to replace the 12v.... but that’s a $200 dollar guess on a battery that is testing in spec.... and $200 bucks buys a lot of gas for the trip...

    My main question is, does that headlight sensor trip a signal when it goes bad that should leave the red triangle on? Or can it glitch out when it’s going bad and send intermittent signals to cause the light to come on, or do you think it’s my 12v going causing the system to act strangely? My hang up that it’s the 12v is that it only throws the light after it’s been sitting for a few hours, so that would indicate it’s losing charge.... but I ran the test on the battery first thing this morning and didn’t give it a chance to charge through the car. So I’m kind stumped.

    Thanks for any advice.
     
  2. Skibob

    Skibob Senior Member

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    I’m going to guess you are using a generic code scanner. The codes(s) are there, your scanner can’t see them. Did you put in or take anything out of the trunk before you started the car and the light went on?
     
  3. Hx214

    Hx214 New Member

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    I did unload the truck before we left that day. I had a 5 gallon bucket of fence paint in there.

    Maybe the sensor got stuck trying to recalibrate, because like I mentioned before it happened again a few starts after I had unloaded everything.

    I went out this morning after letting the car sit over night and no light today.
    I’m going to roll the dice and stick with what I got for the trip. I’ve got a few stops on the way and all of them have parts stores with a battery available, so if something happens I at least have a plan.

    Thanks for the reply SkiBob, made me remember unloading that 5 gallon bucket. Maybe that was the issue all along and my headlight sensor is starting to go.

    Having a hybrid battery fail once makes me panic when that triangle comes up!
     
  4. Skibob

    Skibob Senior Member

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    That’s probably it then. You won’t really know until you get a scanner like the mini VCI with techstream. You need a laptop to install techstream on. If you have a laptop already you can find free version of techstream 12 and download and install it first.
     
  5. audiodave

    audiodave Active Member

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    How
    You have a trickle charger for the 12volt? Give it a charge.
    The Prius charging system is weak.

    Posted via the PriusChat mobile app.
     
  6. Hx214

    Hx214 New Member

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    I have a couple different scanners, my diesel laptops scanner came with software for a ton of different manufacturers that has let me get into airbag lights and ABS bleeding but doesn’t seem to pick up the Prius specific codes.

    I had the car up on my lift today changing fluids and doing last checks and I looked over the sensor in the back for the headlights and everything looked good and tight. I was hoping maybe something was loose in the plug.

    I’m going to look into the Mini VCI scanner. I have a few older laptops here that should do the trick.

    Thanks again!
     
  7. edthefox5

    edthefox5 Senior Member

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    That pops up momentarily upon start up if the 12 volt battery dips below a certain voltage under a READY load. Based on my own experience I think that dip is anything below 10.9 volts thereabouts. Its the only warning you get the 12 volt battery is ready to leave you.

    Its the only code thrown that is not saved.

    Of course it would probably fail the headlight on test too.

    If you have a voltmeter put it across the front jump points don't measure anything at the battery always measure at the front jump point and while watching the DC meter have someone ready the car and watch how low it dips as it boots up. I'm betting it dips below 11 volts
    which is a fail. Its confusing you now with the readings you took because that battery is still healthy enough to recover from that boot up. But not for long.

    A modern battery charger with anti sulphation would probably patch it for a while. I like my new CTEK MUS 4.3. charger. What your doing wrong here is your not maintaining the 12 volt battery because if you did you would notice its going south. Good idea is to throw a charger on the cars battery once a month and see how long it takes to reach 13.8 volts. I do that on all my cars and have never been stranded with a dead 12.

    Im on my second yellowtop. There ok battery's but when they start to fail they fail really fast. I saw that on a routine charge and caught it. I was 2 years 11 months and 20 days into my 3 year warranty. Autozone gave me a new yellowtop.

    I also charge up my hybrid battery using a hybrid battery charger called Prolong like lots of us on this forum. That has given me another 2 years of life on my hybrid battery.

    New 12 V battery time asap.
     
  8. Skibob

    Skibob Senior Member

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    My understanding is water gets into the sensor and corrodes the springs. There is a thread about it here somewhere with people fixing their own.
     
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