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Discussion Starter #1
Questions:
1) Does the TBS light have a way of telling which tire is in need of air?

2) I've had the TPS illuminate a couple times on cold days. (for S. California) Then it goes off. Cold weather air contraction, or something else?
 

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TPMS only indicates low pressure in one or more tires, the only way to see individual tire pressures is with Techstream AFAIK on late 4.4 models, seems to me earlier 4.4 models would show tire pressures in diagnostic mode, but it was removed on later 4.4 models.
 

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You may want to reinitialize the TPMS system following the instructions in the manual in the do it yourself maintenance section on about page 491, the TPMS reset button is above the brake pedal under the instrument panel, not on the instrument panel like pic in the manual appears.
 

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Might be a good idea to, you know, actually check the pressures.
The TPMS shouldn't come on no matter how cold it is.
 

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Discussion Starter #5
Might be a good idea to, you know, actually check the pressures.
The TPMS shouldn't come on no matter how cold it is.
Maybe I'm making an incorrect correlation, but then again....

Blame the Weather for the Tire Pressure Light Coming On

The light has come on three times in 4 months, each on a day that was unusually cold for our LA climate.

At any rate, I just thought since they put in 4 separate wheel sensors, how hard would it be to add code that reads witch sensor and illuminates LF, LR, RF, RR next to the TBS icon.
 

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Colder weather will reduce tire pressures and can cause one or more TPM sensors to activate. I always keep our tire pressures at least at 35psi which so far has prevented activation. Don't know how to alter the mechanisms so that the dash warning system will show which individual tire is low, but another member may have the answer.
 

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Maybe I'm making an incorrect correlation, but then again....
So you haven't actually checked the pressures? The pressure needs to drop roughly 5 psi to activate the alert, more than cold temps will account for. The TPMS is not a substitute for checking pressures.

I run the pressure up a couple lb over what I want, then reset the TPMS system, then lower pressure a couple lb. That way if it drops a few more psi I know about it. But I still check pressure every month or so.
 

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From a practical standpoint you, Kaiso, have two options, actually three.

1. Each tire, including the spare, has a little black cap that screws onto a valve stem. I know it's a lot of heavy dirty work that one can't do with a smartphone or a keyboard, but you could take them off one at a time and test the pressure with a digital gauge Walmart sells for under ten bucks.

2. You could park the car until the temperature gets high enough for the Ideal Gas Law to raise the pressure enough to turn off the light. (Here in New England we've been waiting for that for two years plus three Quarters of a Super Bowl. Finally the pressure came up enough for Edelman to catch the football and the Patriots to pull out Brady's fifth win. Take that Commissioner!)

3. Forget about the light and the whole thing not working the way you want. What does tire pressure matter anyway?
 
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