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Comment by Reubachi | Hacker News Reader

You're intentionally leaving out the fact that a greater and greater number of manufacturer/OEMs are making necessary tools to properly debug proprietary and locked behind contracts. Or, you have a newer car and haven't had to diagnose yet a myriad of growing issues that you can't check in any way shape or form.

Want to link into any car in the last 5 years can-bus for anything beyond simple air-fuel mixture issues? You can't. You can't even reliably go to a mechanic down the road, as they don't carry the 500k a year license from GM for the proprietary OBD2 scanner.

This problem is 10 fold with electric cars, and 100 fold with Tesla or boutique EV manus.

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Also, the info that is exposed to end-users is awful and seems to be getting worse. We have a 2021 Volvo and it has TPMS, but the TPMS info screen on the large infotainment display shows /4 orange dots, one on each tire/ when the pressure in ANY is too low. It doesn’t tell you the actual pressures, or what they should be, just that it needs maintenance. My other 2017 Chevy tells me the ~real-time (takes a few seconds to change) pressures of all 4 tires. I know that the Volvo has this info, and a screen more than capable of displaying that info, yet someone chose instead to treat the user like an absolutely helpless idiot and basically suggest that they should stop using the vehicle immediately and have it flatbed trailered to the nearest dealership /because a single tire is a few PSI low/.

I understand having idiot lights for idiots, and sure, do that on the dash, but please give end users any way to get some actual info. It’s the “door ajar” when the vehicle knows which door but doesn’t disambiguate to the user. It’s bad design, or malicious design to boost dealer profits.

The Volvo is using an iTPMS system, which does not have absolute PSI measurements.

My Audi does this too. And despite the salesman’s insistence that it’s actually better this way, it still bugs me.

To elaborate a bit on what someone else said -- some cars with TPMS systems do not have pressure sensors at all. It is possible to add TMPS to a vehicle entirely via software by analyzing other data from existing sensors. For example, it might be looking at sensor data that looks like:

Steering angle: 0 degrees

LF wheel speed: 305 rpm

RF wheel speed: 293 rpm

LR wheel speed: 302 rpm

RR wheel speed: 285 rpm

In this case, it may be possible for the car to determine that you probably have some incorrect pressures, but it may not know exactly which tire(s) is/are wrong. Nor does it know what the pressures are.

It's true that it won't know the exact pressures, but it certainly knows which tire is spinning faster than all the others (due to the lower pressure, it has shrunk) so it could definitely tell you to check that one.

In fact, your example looks more like one overinflated (or perhaps overheated) tire --- RR.

You seem to contradict yourself in this post. You say they can tell one is spinning faster than all the others, however this one could also easily be the one inflated to the correct pressure, while the other three are overinflated. If the Volvo tells you to correct it and it is wrong, it could keep telling you to overinflate tires indefinitely. This could be why they don’t, which was OP’s original point.

When you inflate them you press the “set” button so it knows what the base is. If one suddenly starts geting more angular velocity constantly than it’s likely it lost air

Yes, if one decreases relative to the other, it’s easy to figure out that one changed.

You still don’t know for sure that it needs inflated, because:

1. setting tire pressures incorrectly is not uncommon

2. That button is user accessible and might be pressed inadvertently or by someone who didn’t set the tires correctly

3. If all tires change in pressure at the same time, it would be undetectable

This is why these systems generally tell you to “check” your tires, rather than inflate a specific one. If they made that assumption, your car could be telling you to inflate an already overinflated tire.

1. Just check the tires. 2. Read the manual 3. Not sure about every implementation but it still possible to tell by storing wheel rpm associated with engine rpm, gear and steering angle the first few miles after setting it.

There are many cars with tpms in the wheel that still won’t tell you what wheel it is or what’s the pressure, so I still much rather have no sensor to deal with trading the “inconvenience” of checking the tires once the light comes on, which is what you would do anyway.

I think you’re misunderstanding me. I’m not complaining about the functionality. I think it is good functionality, and I personally prefer iTPMS.

I was explaining why the engineering of the system dictates the information that the interface provides.

F-150 does it with perfection using circumference alone. It does the exact thing you said cannot be done. I have verified it myself.

It also perfectly calculates distance to empty in miles/kilometers.

The F150 uses direct TPMS sensors. It doesn't need to measure wheel speed to determine pressure, because it has pressure sensors inside of the tires.

2021-2023: https://parts.ford.com/shop/en/us/electrical/other-electrica...

2015-2020: https://parts.ford.com/shop/en/us/electrical/other-electrica...

2013-2014: https://parts.ford.com/shop/en/us/electrical/other-electrica...

And I much prefer this system every time I have to change a tire so not to play the gamble of “will my tpms die before the next change?”. And even if you change them, the chances of an aftermarket one dying and having to deal with that.

I don’t care what pressures the tires have as long as they are good. If I stop to inflate one, I check all of them anyway, with a real gauge. But that’s just me, I know.

Incidentally, every aftermarket TPMS does show all 4 pressures too. Some will even monitor the spare as well.

Unless they are doing some serious wizardry, cars don't know which tire is which. Telling the tires apart was never one of the goals of the TPMS standards.

The transponder in each tire just shouts out its serial number and pressure on 315mhz and then sleeps for a random amount of time. The car counts how many times it has heard the various serial numbers, and assumes the top four most frequently heard serial numbers are its own tires (as opposed to those on the car next to it).

It is sort of stupidly easy to gather location data from TPMS sensors. If I ran a major criminal gang I'd track the cop cars this way. 315mhz is almost VHF, it goes a long way. One receiver per city block should do it. Covering your turf would be easy.

>gather location data from TPMS sensors.

That's one of the revelations from Snowden files. Us govt does this!

Source? I heard of this trick from Schneier, but I have not seen any documents saying the US government is using it. In my experience, 90% of the things people say were in Snowden's documents weren't, so I'm skeptical. https://www.schneier.com/blog/archives/2008/04/tracking_vehi...

it's been a while but check back in a few days. if i can find it again i'll post it here.

Ok, first off - a lot of cars do know which tire is which. Most do it by associating certain TPMS IDs with certain tires. This is what the technician is setting when he does a TPMS re-learn (or reset) after rotating your tires.

Other vehicles actually know which is which without being told. I'm not sure exactly how this is done, but I'm guessing/vaguely recall hearing they do this by using multiple receivers.

As for tracking from a distance - these sensors have very low output power, and a lot of their signal is blocked by the metal wheel. It can somewhat be done but you'll need more than one receiver per block if you want 100% coverage.

Sources: worked as a tire shop technician for a while, messed around with SDR, read a lot online. Also: https://web.wpi.edu/Pubs/E-project/Available/E-project-09111...

The "check engine" light used to feel like a frustrating but economical decision. Modern cars have multiple full color displays now with computers that have all the information they need to at least display fault codes and still just give you "check engine" style warnings.

It's always been this way.

There are lots of vehicles that can display fault codes and other diagnostic information directly through the gauge cluster. Usually they’re hidden in a secret menu. Search “read codes without scanner” on YouTube and you’ll see a ton of examples.

Genuine question: What about if you rotate the tires? (do people still do that?) You would have to reset the data and tell it what tire is where, or it would need 4 antennae for each wheel.

> and 100 fold with Tesla

Uhhh, except I have an OBD-II adapter in mine[0] and combined with an Android app[1] can see in detail basically everything about the car, including individual battery voltages inside the cell pack?

[0]: https://www.scanmytesla.com/adapters

[1]: https://www.scanmytesla.com/

Ok, Great!

You can now monitor a piece of data you have no means whatsoever to adress outside of the tesla ecosystem. which is thrice fold not an issue with "open-er source" ICU vehicles because: 1. no concern for this battery (obvious I guess) 2. you can bring it to the mechanic down the street, 3. You can do it yourself with parts you source with a warranty that the dealer does not care about.

If your battery "starts to go", do you think you can go anywhere besides Tesla, and that they will not first charge you for a diagnostic using their license ODB2 software? Your diagnostic using a non licensed odb2 scanner and....android app will not allow them to bypass the diagnostic you will certainly have to have done by them, because of their insurance/warranty process requiring licensed equipment. ICU manufacturers DO pull the same shit, but you can at least bring the car to a cheaper mechanic who is hopefully footing the bill of the tooling/license.

Say you ARE Able to perform work outside of Tesla, better not tell Tesla that, or your vehicle will be blacklisted.

> Want to link into any car in the last 5 years can-bus for anything beyond simple air-fuel mixture issues? You can't.

Huh, I guess I was just imagining it when I plugged into the OBD-II port on my 2020 Ford and reprogrammed a bunch of engine and transmission parameters to improve performance. I certainly didn't have any proprietary Ford software or hardware.

It is possible for a lot of vehicles, but at the same time there are companies have been trying to make self maintenance and repair difficult.

I am particularly thinking about John Deere. Although not specific to Electric vehicles.

https://youtu.be/EPYy_g8NzmI

*electric

Be happy with your Ford. I had a Peugeot that required proprietary cable and software, and that software works only on Windows XP...

Don't see it in your post history, or any related profiles; care to mention or link to what you did, here or offthread? (I'm @shortstuffsushi everywhere) I also own a 2020 Ford and would be potentially interested in this.

Forscan (Ford and Mazda) is a software you could try, assuming you have a cable like that one[1]. The free version is be able to read, reset and run diagnostic but it cannot change the car configuration. The full version can change the car configuration but you can't buy licenses for because it come from Russia.

There are some boutique companies, and even some oems [2] that provide software to retune your engine but I have no experience, nor desire, to do that kind of tinkering.

1-https://www.amazon.com/Scanner-FORScan-Adapter-ELMconfig-Dia...

2- https://www.mazdaserviceinfo.com/pcm-reflashing

I went through this company: https://www.livernoismotorsports.com/computer-and-tuning

I don't have the expertise to set up all the parameters on my own, but I'm very happy with the tune they provided.

They've reverse engineered everything for you already, and provide firmware that accepts adjustment, and something to install that firmware.

You can't do that with a generic OBD-II compliant tool and Ford's OEM firmware.

This is very common in the BMW world as well.

If I say "You can't shoot someone", and then you shoot them.....sure! Anything is possible.

In your example, have you since taken it to ford and told them you did this? Better not, as you've broken your warranty and they will see this and report that to you.They will put this information on record, and you now have a nightmare selling the vehicle.

Again, and your example is a good one, ICU vehicles and manufacturers are at least addressable/self repairable. This is not the case so much for electric.

Just an FYI, on Amazon you can buy Chinese scanners that decode proprietary OBD2 and do other handy things like the reprogramming for replacement key fobs.

Mine was $150 and came with Honda support. Other manufacturers can be downloaded for $50.

>You're intentionally leaving out the fact that a greater and greater number of manufacturer/OEMs are making necessary tools to properly debug proprietary and locked behind contracts.

isn't that the way every industry intersecting with IT behaves, and isn't there always someone else fighting to open it up, so https://github.com/iDoka/awesome-canbus A curated list of awesome tools, hardware and resources for CAN bus

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