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02-25-2003, 03:34 PM
I saw Twisted\'s post below but I still have some questions.

The manual says to turn the key to position 2 and press the button to set the system. There are only two times you can turn the key to position 2. The first being going from position 1, in which case the car would be turned off. The second when releasing from position 3 after starting the car. Now in both these situations the car is not moving.

So how can it measure and set the <i>pressure</i> if it works off the ABS system and the wheels are not rotating? Wouldn\'t you need to be driving on a straight road to set pressure if it works off ABS? Does it cue to set pressure next time you drive?

Why does it come on sometimes when there is no pressure differential or loss?

Why doesn\'t it come on driving in circles? Is there a sensor that knows when the car is turning? Is there logic that knows certain conditions the car may encounter that do not indicate a flat tire? <br><font color=#65625E><font size=2>
That's just my opinion, I could be wrong.
San Diego, CA

02-25-2003, 03:40 PM
When you reset the tire pressure warning, it really is told to clear it's stats, turn off the light, and start looking at fresh rotation information once you get underway.

It keeps an average tire radius for each wheel based on data gathered while you are driving.

It has access to the steering angle input, and can thus compensate and/or ignore changes in rotation due to turning.

It's looking for consistent long term drop in tire radius - it can ignore occassional brief deviations for wheelslip, etc.

Once in a while, it can get confused - odd surface conditions, temperature changes, etc.

In general, it works pretty darn well - lights up upon about 10 psi drop from normal, early enough that only a careful visual inspection would have caught it.
StoneWalk, Ventura California
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02-25-2003, 03:46 PM

02-25-2003, 03:48 PM

02-25-2003, 03:50 PM
changed pressure in tires.....on my way to portland....get the old red flat warning....hmmmm....pull over at gas station....check pressure...right where i had set them...40fr 37 rear.....had been running 37f 35 i did change the pressuress.... like in the 02...i push the flat button....light goes out...all is well....

When i get to destination again...check pressures just for grin's...still the same.....

on my way back home....accross the causeway...(big bridge)....light comes on again....

hmmm....pull over....40 fr 37 rr....right where i had set them...push the button while rolling ....light goes out....ok..

so monday on way to work....light comes on again....dammit...for sure i've got a low tire now....get to work...nope 40 fr 37 rr....

Call dan up....he says (lol)...did you read your manual on how to reset.....dammit....pull the manual out follow instructions...light out...and stays out....from what i understand...the car "will be learning over the next few miles" after you follow the instructions......that's my best guess....with car stationary, position the tpm light comes on...then goes off...i too was wondering how the hell it guess it goes into learn mode for the next few miles...<br><font color=maroon><font size=1><font>
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02-25-2003, 03:51 PM
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02-25-2003, 03:59 PM
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That's just my opinion, I could be wrong.
San Diego, CA

02-25-2003, 04:40 PM
1. Car running and stationary in 0 and foot on brake.
2. Hold tire monitor button in until light comes on (takes 5 seconds or so).
3. Continue holding button in until light goes out (about 20 seconds).
4. Drive car for several miles.

I follow this proceedure everytime I check the air in my tires. Not once in 12K miles have I had a false alarm.<br>

Agent7 Austin,Texas
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