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Tire pressure light

Discussion in 'Gen II Prius Care, Maintenance and Troubleshooting' started by misslexi, May 18, 2008.

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  1. misslexi

    misslexi New Member

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    Hello all,

    I've recently had OEM touring wheels with brand new OEM TPMS devices installed. Also brand new Falken tires. Tire pressure is set at 42 front, 40 rear. For about the first 200 miles all was good, then the tire pressure light came on. It blinks for a few seconds when the car is started, then goes solid.

    I stopped at the Toyota dealer today where the service writer told me the light is on because I'm running a much higher pressure than what is recommended.

    Anyone know if this is correct? If not, any ideas what the cause might be?
  2. jamesl

    jamesl New Member

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    Why are you running such a high inflation pressure in the tires?

    From my understanding of TPMS the light will come on in under and over inflation issues....

    I would adjust the air pressure to whats recommended and see if the light goes out, if not then you may have a bad sensor.
  3. Ichiro

    Ichiro Member

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    i would just re-set the TPMS (instructions in the manual) and you should be fine...
  4. ZC1

    ZC1 Junior Prius Owner

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    I second that motion.

    ZC1
  5. misslexi

    misslexi New Member

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    My understanding is that higher inflation pressure can lead to improved fuel economy. The tires are rated up to 52 lbs, not that I would run them that high.
  6. walterm

    walterm Member

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    It sounds like the problem lies in the fact that TPMS sensors have to be 'registered' with the car, and you say you got new wheels with new sensors. Did you have the dealer 'register' them to the car (which I recall is something only the dealer can do)? If not the light is just telling you that the car no longer sees any signals from the sensors in the original wheels.
  7. misslexi

    misslexi New Member

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    What I did was:

    Purchased 4 new touring wheels AND 4 TPMS sensors from a local Toyota dealer.

    Purchased 4 new Falken tires online.

    Had a Les Schwab tire store mount and balance the wheels and tires.

    I removed the stock Prius wheels and tires and installed the new package above.

    After the first 200 miles or so, the TPMS light came on. Now it blinks for about a minute when the car is first started, then it goes solid.

    I tried the initialization procedure in the manual, it has not helped. I wait for the blinking light to go solid in IG-ON mode, hold the tire button down and wait for the 3 slow blinks, wait several minutes, power off, power on. The light still blinks for a minute or so, then goes solid.

    Sounds like I need to have the dealer get them "registered". I'm sort of surprised the service writer I spoke with did not mention that. Then again, she said the problem is the tire pressure I'm running which, from what I see in the manual should not be a problem, at least as far as the TPMS is concerned.
  8. misslexi

    misslexi New Member

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    Well, got the bad news: you are correct, the TPMS devices must be registered with the ECU and only Toyota has the computer that can do it. I sure wished the parts dept had told me that when I bought them. The service writer said they will have to unmount the tires in order to get the codes from each sensor. Then it occurred to me that my strategy of leaving the original sensors in the stock wheels for winter driving might have a flaw, and sure enough it does: the dealership confirmed that the Prius cannot store more than 4 sensors (unlike the Land Cruiser and 4Runner) which means I'd have to have them screw with the ECU every season change, for $175 each time. What a cluster.

    At this point I'm going to swap the sensors and try to return the originals back to parts. If they won't take them back I guess they'll be for sale. Anyone need 4 almost new Prius TPMS sensors? :mad:
  9. JHSmith

    JHSmith Camry Hybrid Owner

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    Nobody has questioned this, yet, so I will. Ask the "service writer" what he's smoking? :boxing:

    The TPMS monitors tire pressure and temperature. IF the tire pressure drops BELOW 75% of the "set" pressure, you will get an alert. (I.E., you reset the TPMS when all tires are at 40 psi, whenever the pressure of any one tire drops below 30 psi, you'll get an alert. You get NO alert for overpressure (except a real loud explosion when you try to inflate to 300 psi :peep: )!

    If the "service writer" was correct, then it would be possible for you to start driving (on cold tires) with no alert, then after 5 -> 10 miles get an alert after the tires heat up and the tire pressure increases. :frusty:
  10. misslexi

    misslexi New Member

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    Well, the news is not as bad as I originally thought. I spoke to "my" parts guy at the dealership today, a person who IMHO Toyota is fortunate to have in their employ. He made a few calls and determined that as long as I have the TPMS codes for the wheels, the dealership will twiddle the ECU for me no charge.

    I'm assuming there is some quid pro quo with respect to having my service work done there, which I plan on anyway.

    I feel better now, I think :madgrin:
  11. Bill Merchant

    Bill Merchant absit invidia

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    I'm glad this is working out for you, misslexi. It was an error on the part of the parts person who sold you the new TPMS sensors not to tell you they would have to be matched, and a real bone-head error if the transmitter codes weren't written down. Maybe the dealer "generosity" in not charging you is to compensate for their egregious behavior.
  12. misslexi

    misslexi New Member

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    Here is the last chapter in my TPMS sensor novel:

    Took the car to Les Schwab tire center and had them dismount the tires in order to get the code numbers off the TPMS sensors. Once visible we quickly realized it was not obvious which numbers are THE numbers, there are lots of numbers, everywhere. Both calls to separate Toyota dealers service departments were fruitless (it's probably an 8 digit number somewhere on the sensor, yeah...right).

    In desperation I called my parts guy and explained my predicament; he offered to go talk to his tech buddy back in service and call me back. Ten minutes later I learned that you hold the senor with the valve stem facing up and away from you, look for the square white bar-code-ish looking symbol on the right sensor wing, the number is a 7 character alphanumeric value right above the symbol. They read something like 9FD0177, CE76177, EF50175, 0B2C176.

    I took the vehicle back to Toyota today where they successfully noted the old sensor codes (which I'll need for snow tires) and programmed the new ones into the ECU.

    Total cost to unmount/remount tires $51, to reprogram the ECU $46.50. Of course my time is worth $0 as I'm sure most other folk's is too :rolleyes:

    I'm going to get my summer/winter swaps done at the same time as a service to see if I can get future ECU manipulation done on-the-house, we'll see. The dealership agreed this is an apparent oversight on Toyota's part.

    Hope this saves someone else a headache :angel:
  13. Sheepdog

    Sheepdog C'Mere Sheepie!

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    wow glad winter tires here are the same tires!
  14. stacyh

    stacyh New Member

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    My tire pressure light got stuck on even after I checked the pressure - I took it to the dealership and they said it was the light's problem, not the tires...
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