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Tire Pressure warning light on/flashing

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Terrell, Jul 28, 2022.

  1. Terrell

    Terrell Old-Timer

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    During a long drive (over 1,000 mi) the low tire pressure light came on, so I pulled off and checked all four tires. All OK. Drove again, the light was off, but it came on again after some time (20-30 minutes). Checked all four tires again. OK. Drove further, now the low tire pressure light is flashing. Next morning, before driving, when the tires were cool, checked the pressure. All OK. Started driving and within just a few minutes, the light started flashing.

    It seems totally random - on for 20-30 minutes, then goes off (driving at 70 mph on a hot day). After being off for maybe half an hour, the light started flashing. After maybe ten minutes it went off.

    What does flashing mean? Are the tires over inflated due to long driving, hot day (up to 107˚), or what?
    I drove from Wisconsin into the mountains of Colorado. Does a change in elevation (lower pressure in the mountains) tend to set off the warning light?

    Is the 2010 Prius old enough that the computer is sensing other cars as they pass me? (It seemed that when a couple of other Toyota's passed, the light went on.)

    Do I need new tire pressure sensors? What is going on?

    Thanks for any insight you can give me.
     
  2. ChapmanF

    ChapmanF Senior Member

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    The system doesn't warn for overpressure, so that's not it.

    There could be a slight low pressure that goes away as the pressure rises when the tire heats up.

    The only situation I know of where the light blinks is the indication of a TPMS error, where the light blinks for one minute and then goes solid. The error could be that one of the tire transmitters has used up its battery. One recently went in my 2010. See this post.
     
  3. Tombukt2

    Tombukt2 Senior Member

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    My 13s are all messing up too My '09 has been messed up for a while The brand of TPMS sensors used in most Toyotas through 2013 is a brand called Pacific if you look TPMS sensors up online for a Prius if you look carefully they sell the exact branded models that are in our prii the green label pacific . I usually check and make sure they're the right megahertz which is written on one of the sensors like back by the trunk or wherever the TPMS sensors are it'll say like 311.2 or whatever the megahertz gigahertz range is of the car sensor assembly or computer assembly. I have it wrote down for my 2010 and it's the same for my 09. I saved all the other ones just because so when I went to search for them I could get the exact same ones so there wouldn't be any hullabaloo. Pacific also makes the center caps for most of the wheels on the Toyota's the 15s the 17s especially on the Prius and the Corolla so apparently they are a company that makes wheel and TPMS accessories a lot of them when I look them up online there's thousands of parts made by this company. And if you get one of these modern tools you don't have to sit there with tech or any other system and enter in serial numbers you can wave the wand across each wheel or something and then sit in the car with it and the light will go outer something very similar I saw the guy at the tire store do this He didn't enter squat into any computer nobody cared about any TPMS serial numbers or where they are on the car or any of that. I don't care where any of them are I just want the stinking light out and not flashing and not nothing on all these cars when I bought the cars they were fine so I'm assuming it's just 7 to 10-year-old plus batteries that's what it looks like in the '09 I have them on the bench
     
  4. Terrell

    Terrell Old-Timer

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    Thanks! I could find nothing in my manual about flashing. Since it's a 2010 purchased in 2009 I think it's pretty reasonable to think a TPMS battery has gone dead, or is almost dead. Lasted a long time, though.
     
  5. Tombukt2

    Tombukt2 Senior Member

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    There are four batteries one on each sensor they are epoxied in the TPMS sensor you will need a knife with a chisel edge to dig out the plastic epoxy mess to replace the 2032 type battery that you're staring at through the epoxy The sensors cost about 12 to 14 a pop I just went with the sensors not the batteries then you need to fill up those battery wells with goop or something because I imagining if you didn't the battery might fly out while the wheels going around which should be quite interesting
     
  6. Xterra72

    Xterra72 Senior Member

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    This happened to me. One or more of your tpms sensors are bad and will need replacement. Tpms sensor(s) are malfunctioning and need new ones. That’s my experience anyways.
     
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  7. ChapmanF

    ChapmanF Senior Member

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    The blinking light is definitely telling you about some system error. Given the age of the car, a run-down transmitter battery is a totally plausible explanation.

    If you wanted more than just a plausible explanation before deciding how to proceed, you could look at trouble codes or live data from the TPMS to have more detail on what it's reporting to you.
     
  8. Tombukt2

    Tombukt2 Senior Member

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    Yes in my tech stream the minute I connect to the car at the top of the first page of the screen it shows the four tires I think the TPMS sensor serial numbers or something like that and what have you I just recently got the new TPMS sensors and then just recently bought tires and had them mounted . Now I need to go by my buddies and have him wave as one so I don't have to sit here and text dream and try to remember all the serial numbers and codes to enter for each sensor that seems like a lot of work for putting a light out.
     
  9. Terrell

    Terrell Old-Timer

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    Thanks, everyone, for your helpful advice! I don't have a scan tool, so I took it to Toyota (I have a really good dealer here in Madison, WI). They told me the scan would cost $40, and that if sensors need to be replaced, they cost $150 each (!). Since the car is so old (2010), they said what you all have said, that the batteries in the sensors are likely at the end of their lives, and that when the low pressure light flashes, it means an error in receiving the info from one or more sensor. I could replace all four, or just the ones that are failing. They did the scan, told me that all four sensors had an error code, but after resetting the code, none of them showed an error code, all four were reporting. And "since at some point they will need to be replaced anyway," they said, they did not charge me anything for doing the scan.
     
  10. Tombukt2

    Tombukt2 Senior Member

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    One more time. The sensors that are in your 2010 just like mine are made by a corporation called Pacific if you look on Amazon you can buy four exact replicas of your 2010 TPMS sensors made by Pacific they also make the center caps for your wheels. And that set will cost you $40 I think 44 maybe so that's a far cry from $150 a piece and made by the same manufacture. And they look exactly the same when you hold them in your hand down to the center caps or look identical to factory I know I have a set in my hand right now. So that right there gets you the sensors at your door then if your tire place is worth the crap or you do business with a decent tire place they'll charge you about $5 a sensor to screw one nut to hold them where your other one is or if your cheap like me I had old tires on a set of wheels I sawsauled out a square of the tire the rubber open the hole I just created screwed on my new TPMS sensors took the tires and the wheels with the cutouts in the tires trashed with new sensors on the rims and had my new tires mounted on the rims so I didn't pay the $7 a piece for them to screw on the TPMS sensors because I just don't do that. And the regular mounting balancing and disposal cost me I think it's $17 a wheel where I go and that's nowhere near 150 bucks what we've discussed here and that's just the price of one TPMS sensor at the dealer no matter how good the dealer is. So just know that that's the realness of it all you do what you need to.
     
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  11. Xterra72

    Xterra72 Senior Member

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    Go to Costco and replace all 4. I did mine when I had to replace all 4 tires so no extra cost to open it up. Less than $200 for all 4 sensors. As good as oem.
     
  12. fuzzy1

    fuzzy1 Senior Member

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    This is just an ordinary tire/wheel problem. Don't take it to a $tealer$hip, take it to an ordinary tire shop! The later will be much less over-priced.

    Another, apparently much less frequent problem than a dying sensor battery, is described in my post #6 of the same thread. But very few people seem to have what I did, while many experience end-of-life battery problems, so it is reasonable to address the dying / dead sensor battery first, then come back here if that doesn't fix it.
     
    #12 fuzzy1, Aug 7, 2022
    Last edited: Aug 7, 2022
  13. Terrell

    Terrell Old-Timer

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    Yes, I will go to my tire guys. They do a great job.
    Thanks, all, for the great advice.