[HN Gopher] Solving my truck's TPMS sensor problem with the help... ___________________________________________________________________ Solving my truck's TPMS sensor problem with the help of an RTL-SDR dongle Author : zdw Score : 74 points Date : 2022-08-22 16:19 UTC (6 hours ago) (HTM) web link (www.downtowndougbrown.com) (TXT) w3m dump (www.downtowndougbrown.com) | garaetjjte wrote: | Somewhat related, my post about receiving TPMS signals, but | without SDR: https://milek7.pl/tpmsreceiver/ | throw7 wrote: | TPMS sensors. A solution to a problem you never had. | Congratulations. They have batteries, so it's a gift that keeps | on giving. | jollyllama wrote: | I wonder if you can get a sensor emulator that plugs into a | cigarette lighter and you can program the car to read from | that. It'd be illegal but you could totally find people who | would pay for that. | loeg wrote: | You can just ignore or tape over the dashboard light instead. | BuffaloBagel wrote: | I knew a Firestone / Ford Explorer widow. She had a flock of | kids. | | https://en.wikipedia.org/wiki/Firestone_and_Ford_tire_contro... | loeg wrote: | How would TPMS have helped the Firestone/Ford issue? The | tires weren't spontaneously losing pressure; Ford was | spec'ing a low tire pressure and the tread was separating. | I'm generally supportive of TPMS but struggling to figure out | how your comment is responsive to the grandparent comment. | throwaway0a5e wrote: | Advocating for blindly making things "safer" with no regard | for tradeoffs is like littering in the park. If a few people | do it it's no big deal. When everyone does it you wind with | bloated cars we can't see out of loaded full of tech that | drives up cost, or a trashed park. Thanks for doing your | part. | | And as the other guy mentioned, TPMS doesn't help you when | the spec for the pressure is what's wrong. | CamperBob2 wrote: | Speak for yourself. TPMS is a great feature. Ever drive on a | highway that's so poorly-maintained that you find yourself | wondering if you're getting a flat? Ever find yourself miles | from home with a slow air leak that you need to keep an eye on | to ensure that you can make it to the shop safely? Do you enjoy | crawling around on your hands and knees with a tire gauge, | contemplating the uncertainty principle while you wonder how | much air you just let out of your tire while trying to check | it? | | I've never owned a TPMS-equipped car that wasn't accurate to | within +/- 2 PSI in the 30-35 PSI range, and won't be buying | any such cars in the future. I see a lot of people complaining | about crappy TPMS implementations, but that's something to | blame your cheap-ass automaker for, not the technology itself. | nousermane wrote: | There is also indirect method - ECU precisely comparing each | wheel's rotation speed, with assumption that lower-pressure | tire would have smaller outer radius, thus slightly higher | angular velocity. This method is somewhat common with | European cars. | | It's very cheap (assuming car already has rotation sensors | for ABS, and adding a software routine doesn't cost much | either), and maintenance-free. | | But there are drawbacks, too - it doesn't detect all tires | deflating at the same rate. And also, ECU has to be very | conservative to avoid false-positives, average a lot, pause | comparison when turning, etc. As a result, you only get the | tire pressure warning like 10 minutes later that dTPMS | would've flagged it. | CraigJPerry wrote: | The VAG system circa 2014 - which i think is a Bosch system | used by many manufacturers unchanged, i can't remember the | name of the system but i recall it was version 9.5 of | Bosch's system - was able to notify me of a fairly rapid | puncture (hit a pothole at high speed) within around 300 | yards. The tyre deflated slowly enough to continue for | another 4 miles (albeit at much lower speed) so there would | only have been a few PSI lost at the time it triggered. | | On the whole in that car (Golf R mk7) it did seem pretty | switched on at noticing pressure loss from a slow leak i | had after a tire replacement one time, which was handy | because the tyres were pretty low profile that meant visual | checks were utterly useless. It'd look perfectly fine at | 10psi in a tire that should be at 34psi. | | One other benefit of the ABS system is that when it goes | wrong and the money light comes on, the user's probably | more likely to respond to a "brake service now!" Type | message than a "TP-something or was it TS or oh i dont know | but the car still seems to drive fine so..." | throwaway0a5e wrote: | >contemplating the uncertainty principle while you wonder how | much air you just let out of your tire while trying to check | it? | | This is just a stupid tax on people unable to discern the | difference between theory and practice and if anything life | needs more of these taxes. | myself248 wrote: | It's absolutely a problem I've had. I drove on a flat for | several miles one winter because I thought the sound was just | snow packed into the wheel-well, and driving on snow masked the | funny handling characteristics of a flat tire. | | By the time I got where I was going, the sidewalls were | wrecked. TPMS would've saved me a tire AND a bunch of hassle of | getting it replaced; the puncture was small and would've been | easy to plug if I'd only known to look for it. | lttlrck wrote: | TPMS is very important with run-flat tires because you cannot | easily tell if one has a puncture or is low on air by looking | at it - they hardly bulge at all. | loeg wrote: | Yeah, TPMS can be a real pain in the ass. And the thresholds it | has for reporting true-positives are pretty extreme (~25% low), | because the auto industry objected to the cost of accurate | sensors. | | As far as diagnosing and programming at home, I have a handheld | OBD-II reader ($35) that can report TPMS codes like this from the | car (without a laptop), and also an OBD-II TPM QuickSet ($120) | from ATEQ (a more basic model than the shop had). The QuickSet | tool is configured over USB, then attaches to ODB-II to write new | TPMS codes into the car. It's useful for swapping between summer | and winter wheelsets without a shop. | spockz wrote: | I'm confused why something is needed. On my Ford I can just | "reset" the TPMS after switching wheels from the main computer. | I had to do it once because the shop forgot to do it. | | Why do you need a whole single thing to do it? | loeg wrote: | Like the sibling commenter said, some cars just don't do it | automatically (mine included). | chiph wrote: | Some cars will auto-learn a new sensor just by driving a mile | or so (the Hondas I have had). Others require programming. | Why don't all car makers specify the auto-learning ones? No | idea. Cost maybe. | | The current SUV can be programmed to know 2 sets of five (for | summer + winter sets), and you change between them via a | switch under the steering wheel. It's common for new owners | to get TPMS system errors because the switch got pushed by | accident. | throwaway0a5e wrote: | There's no point in precise measurement because tire pressure | is going to vary widely over temperature and how laden the | vehicle is. | landr0id wrote: | TIL TPMS works over RF. The blog mentions that it's at a super | low power, and not that I'd ever want this, but I can't help but | wonder if it's possible to set up well-placed sensors at a fixed | position on a road to capture IDs going by -- effectively | tracking vehicles themselves. | jaywalk wrote: | I can capture the TPMS data from my neighbor's vehicles from | inside my house, with a barely-optimized antenna. It's not | _that_ low power. | doubled112 wrote: | Similarly, I am almost certain my car catches the sensors in | the summer tires in the garage while I have my winter tires | installed. | | My winter tires don't have sensors, and it takes many KMs of | driving before I get the sensor failure chime. | | The same process repeats every morning. | ce4 wrote: | The sensors should stay off at rest though (There's | acceleration sensors in the that activate them above a | certain rpm value) | function_seven wrote: | Many sensors will transmit once an hour (or some other | long interval) to let the mothership know they're still | alive. Or to warn you of a flat before you've left your | house. | joncrane wrote: | This is definitely true for me. I take my car to the track, | and my spare wheel/tire combos are stacked right next to | where I park the car. When I take short trips around my | town with my track wheels on, the TPMS light never | illuminates. But about 30 minutes into my drive to the | track, it comes on. It turns off again after I park in the | garage again. | pottertheotter wrote: | I looked into this a couple years ago and a company had a | patent for using TPMS tracking for traffic counts (instead of | putting down those pneumatic tubes). | | However, I seem to remember that new cars have been | implementing something different so less and less cars will | have this. | bonestamp2 wrote: | Yes, some cars use the abs sensors to detect rotation | differences and estimate a low tire pressure scenario. | jdeibele wrote: | I was told by two different tire places that my wife's car | (2015 CX-5) uses the ABS sensors to detect if one wheel is | spinning differently than the others. A flat tire rotates | faster than one full of air because it's smaller. | | I had the warning light come on twice recently: once, I | pulled over to the shoulder when an ambulance was | approaching. As I accelerated to get back on the highway, | the warning light came on. I thought I'd run over a piece | of glass or something. Using the gauge showed nothing | wrong. Reset the TPMS. | | Later, we were starting on a 30-mile drive down a gravel | road in Eastern Oregon. The TPMS light came on. I took a | deep breath, kept driving and after we reached our | destination, I reset the TPMS and it hasn't come on since. | | My conclusion is that I accelerated too quickly on the | shoulder and some gravel or debris made a wheel spin | faster. The second time, there was presumably more gravel | on one side of the car and again one of the wheels spun | faster. | | My wife's car is 2WD. I wonder if either would have | happened in an AWD. | rconti wrote: | Nah, it's probably not slight wheelspin because that | would be a normal case that's handled by traction | control. It wouldn't make sense for the system to both | control wheelspin with traction control AND report it as | a low tire pressure condition. Presumably the TPMS alert | would be triggered by a longer term rotational | difference. It happens for all kinds of reasons (eg, | going into colder temps). | jsight wrote: | Newer Teslas are using Bluetooth Low Energy. I suspect that | some other manufacturers might do something similar. | myself248 wrote: | Yes, this is trivial and you can do it in about 5 minutes after | unboxing your first RTLSDR dongle. Just install rtl_433 and | read the commandline help. | | Next step is to make a database that recognizes sensors that | come past at the same time each day, or correlates groups of | four sensors that seem to travel together which probably means | they represent the four wheels of the same car, and that's | where my software-fu falls flat. | mc32 wrote: | Don't license plates work just as well for tracking? And if | it's the person and not the vehicle, phone tracking is more | accurate. | function_seven wrote: | RF tracking would be better if you don't have access to a | location with line-of-sight to the passing traffic. Also | cheaper than OCR-ing camera footage, and can track vehicles | going in both directions, trucks towing trailers, cars with | no front plate, etc. | | Plate tracking is better for determining direction, and is | probably more reliable because TPMS aren't constantly | transmitting. You could miss a car if it doesn't have any | TPMS info transmitting while it passes your station. | | Is phone tracking still possible for the latest iOS or | Android phones? I thought my BLE and MAC addresses are | randomized, but I don't know much about this beyond that | headline. I'm guessing a Stingray type device would still | work though. | kube-system wrote: | > Plate tracking is better for determining direction, and | is probably more reliable because TPMS aren't constantly | transmitting. | | And also because direct-sensed TPMS is only one way of | implementing TPMS. Other implementations use wheel-speed | sensors which are hard wired, not RF. | landr0id wrote: | There are definitely many better ways of doing this, it's | more of a thought experiment. | sokoloff wrote: | Yes, it's possible. | https://m.youtube.com/watch?v=TDYoo7TGNcw&t=7m45s | ruskyhacker wrote: | Yeah, you absolutely can - speaking from experience. | [deleted] | phkahler wrote: | TPMS sensors are almost completely redundant if you have an | ABS/TC module they can passively infer low tire pressure. | | TPMS is mandated now, in part thanks to urging by their makers. | tedmid wrote: | TPMS sensors are much more precise than ABS/radial speed | sensing. | rootusrootus wrote: | Eh, I prefer real sensors. My car tells me which tire is low. | And I can see current pressures for any wheel if I want. Plus I | have sensors on my trailer (which definitely does not have ABS) | so I can monitor the pressure in those wheels as well. | | Using ABS to passively guess if a tire is low is a big | downgrade in functionality. | aaaaaaaaata wrote: | But a decent upgrade in vehicular privacy! | | Things that make you go hmmm... | throwaway0a5e wrote: | Triple redundant if you have a $0.99 gauge (presumably all | drivers have functional eyeballs). | Johnny555 wrote: | My 2 year old car doesn't have TPMS sensors, it just uses the | ABS system to give a vague "low tire pressure" warning, with no | indication of which tire or how low it is. | | I prefer the real TPMS sensors despite the higher cost since | then when the light comes on, I know which wheel it is, and | what the actual pressure is -- if it dropped from 35psi to | 25psi, I can make it a few miles to the next exit, but if it's | 10psi, I probably need to stop now. | NullPrefix wrote: | How does a TPMS mandate existence or inexistence prevent you | from getting that option when buying the car or installing | the aftermarket version? | Johnny555 wrote: | I didn't advocate for or against a TPMS mandate, but I | don't want a third party system because a factory TPMS | display will be built-into the car's instrument paenl, I | don't need to velcro a separate TPMS display to my | dashboard and either hardwire it or keep it charged. Plus I | know that the OEM system is engineered for that car, I | don't have to worry about installing repeaters because | there's too much metal between the sensors and the | receiver. | | But that said, I do believe that the TPMS mandate is | worthwhile, I've been alerted a couple times already to a | nearly flat tire. (both times due to damage while driving, | so I wouldn't have noticed it even if I checked my tire | pressure every time I drive the car, which I doubt many | people do) | NullPrefix wrote: | OK, so you're saying that aftermarket TPMS might not be | convenient, however, like I said in the original comment, | you still have the option to buy the option when buying | the car. | Johnny555 wrote: | Would a pressure reading TPMS system be offered by | manufacturers if they already implemented the cheaper | passive ABS based system? | NullPrefix wrote: | As you said previously, TPMS gives a more verbose output | than ABS based system. That's a pretty obvious selling | point | Johnny555 wrote: | Is it? My car doesn't offer it as an option, it only | offers the ABS based system. Does any car offer the more | granular TPMS system if they already offer the ABS based | system to fulfill the legal requirement? | NullPrefix wrote: | Would you be willing to share the make and model of your | car? | Johnny555 wrote: | 2021 Honda Accord. | | From the owner's manual: | | _Instead of directly measuring the pressure in each | tire, the TPMS on this vehicle monitors and compares the | rolling radius and rotational characteristics of each | wheel and tire while you are driving to determine if one | or more tires are significantly under-inflated._ | | There's no other TPMS option available for that | generation (10th Generation) car at any trim level, not | sure about the new 11th Gen coming out this year. | NullPrefix wrote: | I was kinda in the wrong, that appears to be correct. | Honda is advertising the ABS based system as TPMS and is | not offering any "upgrades". | aaaaaaaaata wrote: | What does "ABS" stand for in this context? | Johnny555 wrote: | It doesn't actually require the ABS (anti-lock braking | system), but uses the ABS wheel speed sensors to count | wheel rotations, so it's essentially a free way to add | TPMS, no additional hardware required since ABS is | already required, just need software to track wheel | rotations. | | https://en.wikipedia.org/wiki/Tire- | pressure_monitoring_syste... | grzm wrote: | Anti-lock braking system | | https://en.wikipedia.org/wiki/Anti-lock_braking_system | loeg wrote: | > I prefer the real TPMS sensors despite the higher cost | since then when the light comes on, I know which wheel it is, | and what the actual pressure is | | What car do you have that reports this level of detail? It's | much more common for cars to pop a generic "low pressure" | icon with zero other details. | slaw wrote: | 2012 Jeep Grand Cherokee and 2015 Jeep Cherokee show tire | pressure in each tire. | rconti wrote: | Generally the cars that have direct TPMS with sensors in | each wheel report pressures (and also throw a warning when | one is low) whereas the indirect systems that infer it from | rotational speed only throw the warning and give you no | more information (eg, which tire is low). | | My wife's 2008 Subaru Impreza had the worst of both worlds | -- the cost of direct TPMS and no more information than the | idiot light. | UniverseHacker wrote: | Lots of higher end cars will show a diagram with the | pressure of each tire labeled. | pkaye wrote: | My Toyota Camry reports the pressure reported on each TPMS | sensor. Only drawback is I don't know when one matches | which tire so when refilling the air, I have to guess a | bit. | Cerium wrote: | I my Nissan Leaf (2012) has a screen showing the current | reading on each tire. | GiorgioG wrote: | My 2016 F-150 reports each tire's pressure. | Johnny555 wrote: | My Ford Transit van shows the numerical pressure of all 6 | tires. Haven't had a low pressure warning yet so I'm not | sure what level of detail it gives, but with a few clicks I | can pull up the pressures on the instrument panel display. | | It also sends the data to Ford so I can see the last read | tire pressure on the FordPass app. | loeg wrote: | That's really cool. | protomyth wrote: | Kia Niro also has numerical pressure for four tires. It | really helped when I noticed one tire dropped a couple of | pounds before the actual TPMS warning on the dash. Took | it in and they patched the slow leak. I am now inclined | not to buy a car without a numeric display of the | pressure in individual tires. It is way too useful a | feature. | mastax wrote: | Hah, my car does have real TPMS sensors but the dashboard | display is such that the only thing it can say is a vague | "low tire pressure" warning, with no indication of which tire | or how low it is. I should get an OBD adapter one of these | days. | jakear wrote: | A basic mechanical pressure sensor is the much cheaper and | more reliable system. | Johnny555 wrote: | How does a mechanical pressure sensor work? I've only | seen electronic ones, how does the mechanical system warn | the driver about low tire pressure while driving? | el_benhameen wrote: | Speaking from experience, OBD will not necessarily help you | here. Something has to put the TPMS data out on the CAN | bus. The rudimentary system in my old Corolla does not do | this, so the only way to debug a malfunctioning TPMS system | is via sdr (or an expensive tool, or a trip to the tire | store). | kube-system wrote: | Not just "the" CAN bus, but the one you're sniffing. Many | cars have multiple busses that carry different traffic. | tedmid wrote: | Yeah that's really frustrating. Different manufacturers | have different offerings here. My Toyota has nothing more | than the lame "low pressure" warning, but my wife's company | Chevrolet actually shows numeric values for all 4 tires. | | Give us the data!!! | nwellinghoff wrote: | We used to have this cool thing called "sense". It was neat. When | your tire was low you could "sense" it through the steering wheel | by holding onto it. Then you got this feeling something was amiss | and you "looked" at your tires. Hmm it didn't look right. So you | pulled out this 2 dollar device called a pressure gauge and | checked the pressure. It was pretty sweet. Had the extra benefit | of tire changes being 25 dollars cheaper per tire as well. It had | one major flaw though. You had to not be a idiot. :/ | mistrial9 wrote: | agree - mandated sensors are a playground for the surveillance | set; make them readily available, sure. | Ristovski wrote: | I wonder, do those sensors have some built-in battery that lasts | a long time, but ultimately the whole sensor needs to be replaced | due to the electronics being potted-in? | | Or is it so low power that it can use some sort of | piezoelectric/MEMS power source that charges it as the wheel is | spinning? | andrewia wrote: | They are battery powered. The battery lasts a few years, and | conserves charge by only reporting pressure every minute after | motion is detected. | bityard wrote: | Yes, they have a battery that lasts a few years. And typically, | the battery alone cannot be changed, the whole unit must be | replaced. | | In my area, all franchised tire shops will refuse to install | new tires on your car without also installing brand-new TPMS | sensors, regardless of the age of the existing sensor. "Sorry, | it's corporate policy." | aequitas wrote: | When I bring my bike to the tire shop for new tires the guy | always cuts the nozzle off and places a new one in. Might | just be a safety/liability thing. Since they're also made out | of rubber, which degrades. | loeg wrote: | Yep, it's a small battery and low-power device. | hulitu wrote: | Battery shall last for 10 years. Ideally you need to replace | the tire before the battery gets empty. | WorkerBee28474 wrote: | Tire Review says [0] | | > the sensors are usually powered by 3-volt lithium ion | batteries, but some use 1.25-volt nickel metal hydride | batteries. There are developments underway that promise | battery-less sensors in the future, having the potential to | dramatically change TPMS markets. | | Also, YouTube has a number of videos on how to change out the | batteries | | [0] https://www.tirereview.com/changing-tpms-sensor-batteries/ | IronWolve wrote: | Never thought about it, but just checked on amazon, TPMS Reset | Tool for my car costs 12 bucks, I was getting charged when I | swapped tires. Sounds like a way to save money. | ars wrote: | I suspect most cars have a manual process available. Mine does, | it takes a while though and involved letting the air out of the | tire for 30 seconds, and then setting each tire to a different | pressure - in my case the car wants to know which tire is in | which position. | | Other cars that don't care about that usually just have a | button on the dash you can press to start the relearn process. | rootusrootus wrote: | Yep. GM cars, for sure, have a cheap tool that makes it trivial | to reprogram TPMS. Some cars will do it themselves, after you | swap on a new set of wheels and drive a few miles. | bandyaboot wrote: | He mentions cloning sensor ids, and indeed some sensors can be | programmed to match an existing sensor. This comes in very handy | if you have a set of winter tires. You can have multiple sets of | tires that have a common set of sensor ids allowing you to swap | sets in and out without having to reprogram the tpms. | loeg wrote: | Oh, that's smart. I just reprogram when I swap. | 1970-01-01 wrote: | Here's a tip for everyone. If you have 1 bad TPMS sensor, you're | about to have 4 or 5 bad TPMS sensors. Replace all of them at the | same time. Most will now tell you if they have low voltage. | powerhour wrote: | Headlights, too. Basically anything that came from the factory | in pairs or above. | throwaway0a5e wrote: | Pretty much everything on a car lasts between 100 and 400k | with a 100k error bar. There is no reason to be replacing the | overwhelming majority of stuff in duplicate. | andrewia wrote: | This is a really interesting article. One question answered for | the author: I believe TPMS sensors have an RFID-style mode, so | that handheld programmers can access them without waiting for the | slow reporting period. | | I have experience with how finicky these sensors can be. I | installed a radar detector in my car (legal in my state, and wise | considering the unusually aggressive speed enforcement that | appears once every few weeks along the highway I drive). I | stashed the radar detector's control box in some empty space | between the glove box and an air duct. The TMPS receiver module | is also located in this area and cannot receive signals while the | radar detector is powered on. I assume this is broad-spectrum EMF | and I need to layer the control box in aluminum foil. | itsyaboi wrote: | Consider using a foil tape: | https://www.amazon.com/dp/B018RDZ3HG Added bonus of the end | result looking vaguely lunar module-esque: | https://upload.wikimedia.org/wikipedia/commons/2/2a/Apollo16... | mxuribe wrote: | > ...and I need to layer the control box in aluminum foil. | | I don't know why, but that sentence is just awesome! Maybe to | me it just sounds so MacGyver to me. Either way, very cool! ___________________________________________________________________ (page generated 2022-08-22 23:00 UTC)