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Discussion Starter · #1 ·
I don't know if this is just my Cruze or not but I have noticed that when putting air into your tires that the tire pressure display in the dash doesn't update the new psi amount when the car is turned on but if the car is off it's updated when you turn it back on. Is this by design or not normal?
 

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Not knowing how the control modules work, it may be that that information is only parsed at startup as it is not a critical piece of information relatively speaking.
 

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I'd assume it's done at intervals when driving, it does not appear to be a continuous monitoring.

In order to provide the desired safety benefit, it'd have to alert you if pressure decreased while on the road.
 

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I'd assume it's done at intervals when driving, it does not appear to be a continuous monitoring.
Because the sensors are battery powered, they do not operate in real time but only transmit updates "as needed". They will transmit under certain conditions (such as a large pressure fluctuation) as well as periodically when driving. That's most likely what OP is seeing. I don't think the car being on or off makes a difference.
 

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Discussion Starter · #5 ·
Once I had to stop at a truck stop for air. I left the car on and turned on the tire monitor on the screen. Then I'd put a little air in the tire and check the dash to see how much I put in but in order to see that I had to turn the car off then back on with the updated psi. I didn't have a tire gauge on me.
 

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Once I had to stop at a truck stop for air. I left the car on and turned on the tire monitor on the screen. Then I'd put a little air in the tire and check the dash to see how much I put in but in order to see that I had to turn the car off then back on with the updated psi. I didn't have a tire gauge on me.
Interesting. That's not going to trigger the sensor to send. It has to be something about the received data not making to the screen. I wonder if changing the screen and coming back to it would update it.
 

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Interesting. That's not going to trigger the sensor to send. It has to be something about the received data not making to the screen. I wonder if changing the screen and coming back to it would update it.
I wonder if it works the other way around. The wheel sensor is idle until it receives a request from the BCM, then it sends the info. That would allow for the sensor to remain idle most of the time, but to update on a regular basis and also when the screen is selected. Just speculation.
 

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I wonder if it works the other way around. The wheel sensor is idle until it receives a request from the BCM, then it sends the info. That would allow for the sensor to remain idle most of the time, but to update on a regular basis and also when the screen is selected. Just speculation.
Two problems with that theory: First, the sensor would have to have a receiver (as well as a transmitter). Secondly, it would have to have the receiver powered up at all times. That's going to eat batteries pretty fast.

From my understanding, the sensor is tripped by a centrifugal switch as well as by pressure change. I'm not sure how the latter is implemented, but I could see how someone could design a switch that would be tripped by rapid loss of air. (It may not work so well for increase of air.)
 
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