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Discussion Starter #1
Had my Bolt about 4 months; 3300 miles. My wife is learning to accept her now second place position :).

Crisp Autumn weather just starting to creep in here in SW Florida. Tire pressure has dropped to 32 in all tires (myChevrolet app) but no notice of anything amiss from the tire pressure light on the instrument cluster. TP light does come on briefly at startup.

Local gas station air supply gauge confirmed 32 lbs in each tire.

Q: Is the tire pressure cluster alert light threshold lower than 32 lbs or just not working properly for me?
 

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TP light does come on briefly at startup.
from page 278 in the manual: "The low tire pressure warning light may come on in cool weather when the vehicle is first started, and then turn off as the vehicle is driven. This could be an early indicator that the air pressure is getting low and needs to be inflated to the proper pressure."
 

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I haven't had my tires quite that low, and I haven't seen the warning light while driving the car, but one time I checked the vehicle status in the Onstar app and it showed a warning that one tire had dropped to 34. I suspect that the app and the instrument cluster have different thresholds - they only want to warn you while driving if the tire is seriously low.
 

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Discussion Starter #4
I haven't had my tires quite that low, and I haven't seen the warning light while driving the car, but one time I checked the vehicle status in the Onstar app and it showed a warning that one tire had dropped to 34. I suspect that the app and the instrument cluster have different thresholds - they only want to warn you while driving if the tire is seriously low.
Indeed, but what constitutes seriously low? I would have thought a pressure of 32 instead of 38 would initiate an alert. It does in the app, why not on the instrument cluster?

************************************************************************

I'm curious as to whether anyone has seen the instrument cluster low tire pressure alert and at what (subsequently determined) reading.
 

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Discussion Starter #5 (Edited)
from page 278 in the manual: "The low tire pressure warning light may come on in cool weather when the vehicle is first started, and then turn off as the vehicle is driven. This could be an early indicator that the air pressure is getting low and needs to be inflated to the proper pressure."
Thanks XJ12 but I was explaining the context. Earlier in the manual (about page 111) it states that this indicator along with others comes on at startup; expected behavior, IMO.

But more to your point, low pressure alerts generally can (incorrectly) come on when tires are replaced as well. As the car is driven, they turn off.

I do not think my issue is anomalous. Perhaps the threshold is too low.
 

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Today (overnight temp = 31; am temp = 37) my tire pressure warning icon came on for the first time! DIC said pressures of 30 & 31 in left two tires. NO indication of low pressure in the right side tires. Changing to the tire pressure screen showed pressures of 32 in both right tires and the 31 & the 30 on the left. Checked the doorframe to find 38 psi is the recommended cold tire pressure in each of the 4 tires. Went to Krogers (plug for free air providers) and inflated to 38 as best I could see on the sliding (not a digital setting) gauge. Back in the car, the screen said 38, 38, 38, & 39. Warning lights all off. Seems like, in my Bolt, 32 psi is ignored and 31 psi is a "notifiable" pressure.
 

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Discussion Starter #7
Today (overnight temp = 31; am temp = 37) my warning icon came on for the first time! DIC said pressures of 30 & 31 in left two tires. NO indication of low pressure in the right side tires. Changing to the tire pressure screen showed pressures of 32 in both right tires and the 31 & the 30 on the left. Checked the doorframe to find 38 psi is the recommended cold tire pressure in each of the 4 tires. Went to Krogers (plug for free air providers) and inflated to 38 as best I could see on the sliding (not a digital setting) gauge. Back in the car, the screen said 38, 38, 38, & 39. Warning lights all off. Seems like, in my Bolt, 32 psi is ignored and 31 psi is a "notifiable" pressure.
Thanks for the data point, surgeonFWW. Very glad to hear of the threshold.

It may seem like a trivial matter but, while I love this car and strongly admire the engineering that went into it, I think it is a good idea to remain on yellow alert over any early-life RT software, especially given the considerable complexity of this software development job.

And, importantly, this is where all of us can be of help in making a great product even better. I expect edge conditions to show up, some trivial, others less so and this forum is a great way to pass this information onto the Bolt developers.
 

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All TPMS systems have a threshold setting to turn on the lamp. Your car offers a pressure readout too.
What more do you need. A valet to air up your tires and wipe your butt too. JHC!
 

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Indeed, but what constitutes seriously low? I would have thought a pressure of 32 instead of 38 would initiate an alert.
The TPMS system isn't designed to keep your tires at the recommended pressure, it's designed to warn you when they're at an unsafe pressure. Those are two different things.

Just as some people like to overinflate their tires to improve gas mileage, some like to underinflate to increase comfort and shorten emergency braking distances. Therefore the designers doubtless left a fair bit of margin so that people who want their tires underinflated don't get constant warnings.
 

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Discussion Starter #10
All TPMS systems have a threshold setting to turn on the lamp. Your car offers a pressure readout too.
What more do you need. A valet to air up your tires and wipe your butt too. JHC!
I think you were confused by my question. My intention was to learn if it was likely my TPMS light was operational or not, and at what threshold it should alert. Better to inquire here about this functionality to gain a better understanding than go running to a dealer unnecessarily.

Further, there has been ample evidence posted on this board of likely RT software issues in the Bolt's current (and earlier) releases. As a retired software developer, I have a particular interest in the quality of products I purchase that have software components. And when I see indications that there may be issues, I will investigate and speak out on them. That is at least part of what this board is intended to support, don't you agree?
 

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The question of whether a warning light works or not is always in our minds (I co=piloted a plane once that did not get "three green" for the landing gear. We switched lamps to find that they all worked. We dumped fuel and set the "dark" wheel down last. It held up. Mud on takeoff had blocked the switch.)

In the case of tire pressure, it is perfectly OK to go to the air pump station, bleed one tire down to 30 psi and check the dashboard for BOTH indications: the red "saggy tire" icon, and the actual psi indication. Then fill to 38 and drive, knowing all systems are "go"!
 

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I think you were confused by my question. My intention was to learn if it was likely my TPMS light was operational or not, and at what threshold it should alert. Better to inquire here about this functionality to gain a better understanding than go running to a dealer unnecessarily.

Further, there has been ample evidence posted on this board of likely RT software issues in the Bolt's current (and earlier) releases. As a retired software developer, I have a particular interest in the quality of products I purchase that have software components. And when I see indications that there may be issues, I will investigate and speak out on them. That is at least part of what this board is intended to support, don't you agree?
I think you've confused yourself. Common sense isn't very common. Speaking out is fine and I do it often. I don't post wonderment or contribute to it. The fact is the IPC has a bulb check mode and if you use it, you'll know if your TPMS lamp is capable of illuminating without wondering.
Remove the confusion of operation and things become very clear :nerd:
 

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The question of whether a warning light works or not is always in our minds (I co=piloted a plane once that did not get "three green" for the landing gear. We switched lamps to find that they all worked. We dumped fuel and set the "dark" wheel down last. It held up. Mud on takeoff had blocked the switch.)

In the case of tire pressure, it is perfectly OK to go to the air pump station, bleed one tire down to 30 psi and check the dashboard for BOTH indications: the red "saggy tire" icon, and the actual psi indication. Then fill to 38 and drive, knowing all systems are "go"!
Why not just look at the tire pressure display readout screen. Use the BULB TEST feature on the IPC when you start the car. When you power up the car, all the lamps light. Look for the TPMS icon to light up and you'll know it's capable if it does. It's simple and easy without complicating things and over thinking something so simple.
I use the K.I.S.S. method for everything. It's simple and it's been around for a long time.

Simply stated as Keep It Simple Stupid. It's an old saying, but a very good one >:)
 

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All TPMS systems have a threshold setting to turn on the lamp. Your car offers a pressure readout too.
What more do you need. A valet to air up your tires and wipe your butt too. JHC!
I think the OP (and myself) are most curious if anyone knows what the alert threshold might be. I can tell you that at 27-29 PSI mine did not come on and the other night I would not be surprised if they were even a few PSI lower considering the colder temps. While you're right that the pressure readout is always there, that is a screen that I have looked at all of a once the entire time I have owned my car. I don't find it accurate enough to trust it for anything besides a ballpark within 2 PSI (ish) as compared to my nicer gauge. I'm kind of curious what defines unsafe as like someone else said, that is probably their cutoff. 24-25 (which is very well where I could have been the other night) seems unsafe to me. I'm guessing it is something lower than 20 then...
 

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While you're right that the pressure readout is always there, that is a screen that I have looked at all of a once the entire time I have owned my car. I don't find it accurate enough to trust it for anything besides a ballpark within 2 PSI (ish) as compared to my nicer gauge.
Since I usually keep my dash display on the trip panel, the tire pressure readout is literally one button tap away. I think it's worth the time and effort to press that button at least once during any trip that is over 10 minutes in length, and at least once a week even if you've done nothing but short errands. On a long trip, make it a habit to check pressure right as you start out, just like you check the current battery state-of-charge. We only have two things in the entire car that we have to actively keep 'full', tire pressure and battery, so it's not that hard to pay a little attention to both.

It's a habit that needs to be cultivated, because the payoff/penalty is so big. If you'd had the same habit I have, then driving at 27psi for any distance would simply not happen, you'd have spotted the problem very early in the drive. One button press is extremely cheap in cost (or two presses, if you count the one to return to the trip screen).

As a side note, I can see a measurable reduction in driving efficiency when dropping from 41psi to 38, so keeping an eye on pressure even when you're way above 'unsafe' levels is a good thing.
 

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I think the OP (and myself) are most curious if anyone knows what the alert threshold might be. I can tell you that at 27-29 PSI mine did not come on and the other night I would not be surprised if they were even a few PSI lower considering the colder temps. While you're right that the pressure readout is always there, that is a screen that I have looked at all of a once the entire time I have owned my car. I don't find it accurate enough to trust it for anything besides a ballpark within 2 PSI (ish) as compared to my nicer gauge. I'm kind of curious what defines unsafe as like someone else said, that is probably their cutoff. 24-25 (which is very well where I could have been the other night) seems unsafe to me. I'm guessing it is something lower than 20 then...
Deflate 1 tire by one lb. at a time and wait to see then the light comes on if you need to know.
Make sure to give it a little time to register/react to the adjustments. I'll bet your nice gauge
is a China made POS and I'll bet the TPMS sensors are more accurate too :eek:
 

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I was looking at the TPMS and found we have the ability to set the desired PSI from 0 to 596 psi.
I reset mine to 44.9. IIRC, the TPMS lamp trigger pressure is about 24 psi and I have not been able to find a reset for that set point. I would guess its tied to the inflation pressure stored in the module.

Based on the info at hand, I would say 15 psi below the stored pressure data. This is just an EWAG!
 

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