Tire Pressure Monitor in 2006

B

blue2006

New member
ok, this may be a dumb question, but i'm curious to know how the tire PSI is fed into the car's computer to trigger the low PSI warning...
last night i went over a much bigger curb than i thought, the front side went over nice and smooth because i nudged it up aginst the face and then went over slowly, but the rear came over too quickly and i believe i dislodged or over compressed the tire and blew it out...when i came out of a store about 10 mins after this incident the tire was dead flat. I dropped it off this AM so i'll know tonight what happened.
so i swapped for the spare last night and this morning when i came out to go to work, the PSI warning was on, sure enough the spare was low by about 4lbs...it got me thinking, how does the car-puter know? Is there some RF chip in the wheel?

one more question, has anyone had trouble airing up these new tires? i only had a few minutes to spare, so i hit the first station on my commute and i couldnt get any air to go into the tire, the air line was active, but when i plugged it onto the tire, nothing...
 
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There is an RF transmitter in the stem of each tire (including the spare). I believe they send an "ok" signal, rather than a low signal because I remember hearing stories of people switching rims and they light coming on if they get too far away from them, but it would go off they were stacked in the garage next to the truck.
 
N8G said:
There is an RF transmitter in the stem of each tire (including the spare). I believe they send an "ok" signal, rather than a low signal because I remember hearing stories of people switching rims and they light coming on if they get too far away from them, but it would go off they were stacked in the garage next to the truck.
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Correct. The system alerts you when the tire pressure goes below 26.8 psi. You would want to put the max air pressure (40+) in the spare and carry a pressure gauge in the truck, so you can lower it when needed. By keeping the max pressure in the spare you will not have to add air so frequently.

Koz
 
pretty cool, it would be better if it told you WHICH tire is low...on my way home yesterday i stopped to correct the airpressure and lose the warning light. Despite checking each tire twice and filling each tire to the required 32psi, the low pressure light still stays lit on the dash...could this be because i don't have the 5th wheel on the car yet? (its still at the shop) or are you supposed to reset the warning soemhow?
i have not yet had the time to browse the manual, so im sorry if this is answered in there...
 
Scuba4Runner said:
Do the batteries on these sensors every go bad? If so, how does one replace them?
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I read they're suppose to last for 5 yrs. I don't know if it has replacable batteries. I think the Toyota TPMS are pretty expensive too. IMO, I rather not have the TPMS.

My buddy at a tire shop says Honda ones go for about $18. He wanted to get me a spare, but I have no idea whether it'll work on a Toyota probably due to different frequencies.
 
The TPMS is a U.S. Government mandate. It's required on all 2006 and newer cars. Toyota tried a "passive" system, which looks for one tire being lower than the rest based on rotational speed measured by the anti-lock brake system. They must have started having trouble with it, though - TSB's have recently appeared for the 04-06 Lexus RX 330 and the 04-05 RAV4 passive TPMS. It can be fooled by certain driving styles and conditions. The Lexus RX 350 and the new RAV4 both have the active TPMS like the 4Runner.

Looking at the picture in the Service Manual, it appears that the sensors are powered by a regular coin-size lithium battery. However, by the way they describe it, you would destroy the sensor in the process of getting to the battery. So they do expect you to replace the whole thing when the battery dies.
That's probably not a bad idea, since the sensor is also the valve stem, and you should replace valve stems when you replace tires.

Don't know if Honda uses the same design, much less the same frequency. Toyota is on 314.98 MHz, according to the "New for 2004" guide that talks about the system on the 4Runner.
 

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I had a flat tire and took it to a local tire shop for repair and they broke off sensor when removing tire from rim and tried to pull a fast one on me by saying it was already broken,I drove 4Runner in and tire had a leak.,but tire light never came on.They ended up paying for sensor and it was around $100 for the sensor and seal kit.Do the math $100 X 5 sensors =$500.When these sensors start to go bad I will remove the light in dash.My light started flashing and one of the other sensors went bad and it was the one in the spare.The Toyota tech said for some reason the spare
sensor seems to go out more than any other tire.When he was troubleshooting system he hooked up Toyota Diagagnostic reader to port inside 4runner and the bad sensor will read -12psi
and the other ones will read correct psi,he filled tires up with air
one at a time until he found the bad sensor.the system will tell you that a sensor is bad but not which one.It would be cool if
my display would also read tires PSI instead of low limit idiot light because sensors actually measure and send out PSI for each tire.
 
$100 is a high price to pay for a sensor. That's almost the cost of a new tire. Hopefully they will come down in price in couple of years when it's time to replace them.
 
so to add my update, it ended up being a trashed tire, the side wall had blown out and was not repairable; nice size crack too. went to a Mavis discount tire, they couldnt get the michelins that were on the truck. called 2 dealers locally, one said he coudn't even find it in his system, the other said it would take a few days and cost $250. i found one at tirerack.com for 196.00 +16.00shipping.
luckily the rim isn't bent, or at least it didnt seem bent to the tire tech, hopefully its good...i dont want to have to get a new rim already, i ojnly have 3000 miles on her...what a PITA
 
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