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Getting chilly around here right now (down near freezing in the morning) and I noticed a tire pressure warning light go on when I fired up to go to work.

Checked the DIC and saw pressures as low as 21 psi., so I hauled out my air source (a Scuba tank I've used for many years to fill tires at the track on the race cars) and topped the tires off. I use a pretty good Afco oil filled gauge - in road racing, a couple of psi either way can make big handling differences - and after I got back in the car I checked the DIC again.

The DIC showed 2-3 psi lower than the gauge. My bet would be on the gauge for accuracy but I thought I'd post in case anyone else has ever checked the accuracy of the in car system with a recently calibrated gauge of known accuracy.
 

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Bill, my (not the cheapest) handheld Digital is pretty darn close +/- a half pound. :thumbs:

HTH

Steve
 

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My old tire gauge(metal not the cheap plastic) works within an 1/2 pound of the DIC.
 

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Seems pretty obvious that if you know for certain that the gauge is accurate, then the DIC is wrong. Am I missing something?
 

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My DIC is off by 8-10psi. I've had the dealer check it with 3 different gauges, and my expensive digital gauge. My tires currently have 32psi in them, the DIC shows 24!! It's been an issue ever since I bought the car!
 

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My DIC is off by 8-10psi. I've had the dealer check it with 3 different gauges, and my expensive digital gauge. My tires currently have 32psi in them, the DIC shows 24!! It's been an issue ever since I bought the car!
wow...

my instrument panel always reads higher than any gauge I have...

So, is the instrument panel wrong , or the device(s) inside the tire(s)
that feed the instrument panel ?
 

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well, I haven't checked mine but according to the DIC, I have 3 different numbers. I wonder if the sensors have to be a certain temperature before they read right? has anyone checked the manual? regardless, I'd go off my "known" gauge. we have a big tempurature change going on in Houston. 80 today and it was freezing a few days ago. this throws it off a bit for sure.
 

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The sensors in the tires are built to an accuracy requirement. Probably within a pound or so of the actual. The readings are transmitted to the BCM which then displays them. The BCM code does not interpret the data, it just presents it on the DIC when commanded by the driver. The engineer in me says that the primary error point is the sensor in the tire. After that its not processed information.

I bought a hand held reader that I use to read directly from each in tire sensor. I can also use it to reset the in tire sensor. Every tire shop has one by now. Have them check the information coming from each sensor and compare that with a real time reading of the pressure and you should know what the accuracy is.:thumbs:

I bought the device because I was getting continuous TPMS reading warnings in the wife's Kia. It displays only on or off condition, not pressure or which tire is alarming. What I discovered was that one of the wheel sensors was consistently reading 2 pounds low. I measured the pressure and the wheel was still alarming. When I raised the pressure 2 pounds, the alarm went off. So in this instance, when I set the pressure in all four wheels exactly at the recommended pressure as measured with a good mechanical dial indicator gauge, the alarm continued to present. Once I found the offending wheel and raised that pressure 2 pounds as measured by the mechanical gauge, the wheel sensor transmitted the increased pressure (but 2 pounds low) and stopped alarming.

One test you might try is swap wheels with a known good car and verify that once relearned the TPMS presents accurate data. Then you know that the wheels are transmitting bad data.
 

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My experience is +/- 1/2 lb
 

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I just looked it up and good grief I would have never guessed what’s in one of the units.

In the range of -40C to 125C and tire pressures of 15 to 115 the combined accuracy and precision is +/- 1.5 psi.

Here is a link to the site of one of the manufactures:
Tire Pressure Monitoring Sensor, TPMS

They have pressure, temperature and motion sensors inside each unit.
 

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Don't have sensors in the '06, but on my bikes you have to be moving for about a quarter mile before you get a reading.
My Sol has 'dry' air in the tires and the pressure has stayed constant from August to now whis is a 40 degree difference in morning temperature.
I have always wondered how moisture in the tire affects the TPMS. I've never had problems with TPMS sensors that had nitrogen in them but with non dried compressed air there seems to be a problem eventually. My truck never had a problem until I put air in one of them. That one always sets off an alarm if it gets to 30lbs. Not suppose to until it detects 28. The other Nitrogen filled tires never a problem. Of course the Sol hasn't either yet. I am waiting but they do have air not dried or nitrogen filled.
 

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I believe the motion sensor is to wake up the pressure sensor from a low power mode so that the batteries last a nice long time.

For the person above getting 8 psi or more differences I would suggest replacing the sensors. I doubt the dic is doing something wrong unless it's set to metric or something. :)
 
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