21 ms·
Solving my truck’s TPMS sensor problem with the help of an RTL-SDR dongle
- Ristovski 4y agoI 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?
- WorkerBee28474 4y agoTire 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/ https://www.tirereview.com/changing-tpms-sensor-batteries/
- andrewia 4y agoThey are battery powered. The battery lasts a few years, and conserves charge by only reporting pressure every minute after motion is detected.
- loeg 4y agoYep, it's a small battery and low-power device.
- hulitu 4y agoBattery shall last for 10 years. Ideally you need to replace the tire before the battery gets empty.
- bityard 4y agoYes, 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 4y agoWhen 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.
- andrewia 4y agoThis 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.
- mxuribe 4y ago> ...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!
- itsyaboi 4y agoConsider using a foil tape: https://www.amazon.com/dp/B018RDZ3HG 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/Apollo16LM.jpg https://upload.wikimedia.org/wikipedia/commons/2/2a/Apollo16...
- landr0id 4y agoTIL 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.
- mc32 4y agoDon't license plates work just as well for tracking? And if it's the person and not the vehicle, phone tracking is more accurate.
- landr0id 4y agoThere are definitely many better ways of doing this, it’s more of a thought experiment.
- function_seven 4y agoRF 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 4y ago> 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.
- sokoloff 4y ago
- phkahler 4y agoTPMS 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.
- Johnny555 4y agoMy 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 4y agoHow does a TPMS mandate existence or inexistence prevent you from getting that option when buying the car or installing the aftermarket version?
- Johnny555 4y agoI 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 4y agoOK, 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.
- bandyaboot 4y agoHe 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 4y agoOh, that's smart. I just reprogram when I swap.
- rnitchy 4y agodo you need to store them away from the vehicle when you park? i could imagine parking a car next to your stacked up winter tires in a garage would cause issues
- bandyaboot 4y agoI thought that might be an issue as well, but it hasn’t been. They’re stored about 15 feet away from the car.
- xnzakg 4y agoThe article also mentions this, many (most?) TPMS sensors to to sleep and wake up on movement. So as long as the other set of wheels isn't moving it should probably be fine.
- IronWolve 4y agoNever 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 4y agoI 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 4y agoYep. 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.
- loeg 4y agoYeah, 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 4y agoI’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?
- chiph 4y agoSome 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.
- KennyBlanken 4y ago> Why don't all car makers specify the auto-learning ones? No idea. Cost maybe. Because auto-learning ones don't encourage a trip to the dealer, where the customer will go for new tires as well etc.
- loeg 4y agoLike the sibling commenter said, some cars just don't do it automatically (mine included).
- 4y ago
- throw7 4y agoTPMS sensors. A solution to a problem you never had. Congratulations. They have batteries, so it's a gift that keeps on giving.
- jollyllama 4y agoI 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 4y agoYou can just ignore or tape over the dashboard light instead.
- CamperBob2 4y agoSpeak 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 4y agoThere 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.
- deleted 4y ago[deleted]
- 1970-01-01 4y agoHere'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 4y agoHeadlights, too. Basically anything that came from the factory in pairs or above.
- throwaway0a5e 4y agoPretty 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.
- garaetjjte 4y agoSomewhat related, my post about receiving TPMS signals, but without SDR: https://milek7.pl/tpmsreceiver/ https://milek7.pl/tpmsreceiver/
- nwellinghoff 4y agoWe 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 4y agoagree - mandated sensors are a playground for the surveillance set; make them readily available, sure.
- deleted 4y ago[deleted]
- anonymousiam 4y agoHe could also have used the "mayhem" firmware for HackRF to troubleshoot his problems. Not only does it receive and decode the TPMS data, but it also allows you to spoof and transmit TPMS data. https://github.com/eried/portapack-mayhem https://github.com/eried/portapack-mayhem
- spydum 4y agoI think it's cute he assumed he got a bad sensor replaced.. following the story, it's more probable the shop replaced two good sensors and never the actual bad one until the end. Seems far more reasonable explanation of the whole episode.
- maxerickson 4y agoThe author more or less watched them swap the sensor that had initially been replaced. (and had the ids of the remaining sensors)
- dougg3 4y agoAfter the initial trip to the tire shop, 2 of the sensor IDs that were previously working were still working. And I had 2 brand new valve stems. So they definitely changed out the bad one, along with another one. I just got super unlucky and one of the new sensors was defective.
- 1-6 4y agoTPMS’s should go into hibernation when there’s no movement. I wonder if battery packs can be designed to last a lifetime.
- gregmac 4y agoI have an RTL-SDR that collects sensor data via rtl_433 [0] and publishes it to MQTT, which I use for temperature and contact sensors. I found it interesting that I pick up a fair amount of TPMS data from (what I presume are) people driving by. {"time":"2022-08-03 08:25:13","model":"Schrader","type":"TPMS","flags":"ab","id":"555551E","pressure_kPa":267.5,"temperature_C":57.0,"mic":"CRC"} {"time":"2022-08-06 04:53:23","model":"Schrader","type":"TPMS","flags":"d5","id":"2F656AA","pressure_kPa":585.0,"temperature_C":120.0,"mic":"CRC"} {"time":"2022-08-06 06:15:29","model":"Schrader","type":"TPMS","flags":"af","id":"4BAAC5B","pressure_kPa":227.5,"temperature_C":35.0,"mic":"CRC"} {"time":"2022-08-08 10:24:43","model":"Schrader","type":"TPMS","flags":"af","id":"553AAD5","pressure_kPa":232.5,"temperature_C":120.0,"mic":"CRC"} {"time":"2022-08-08 10:35:39","model":"Schrader","type":"TPMS","flags":"5a","id":"AAB8576","pressure_kPa":452.5,"temperature_C":43.0,"mic":"CRC"} {"time":"2022-08-08 10:58:22","model":"Schrader","type":"TPMS","flags":"ad","id":"6FF5667","pressure_kPa":427.5,"temperature_C":56.0,"mic":"CRC"} {"time":"2022-08-09 21:34:49","model":"Schrader","type":"TPMS","flags":"6a","id":"BAD22B2","pressure_kPa":212.5,"temperature_C":132.0,"mic":"CRC"} {"time":"2022-08-09 23:31:35","model":"Schrader","type":"TPMS","flags":"6a","id":"AB5E5B6","pressure_kPa":545.0,"temperature_C":163.0,"mic":"CRC"} {"time":"2022-08-10 16:49:55","model":"Schrader","type":"TPMS","flags":"57","id":"B56AED6","pressure_kPa":427.5,"temperature_C":36.0,"mic":"CRC"} {"time":"2022-08-11 00:58:24","model":"Schrader","type":"TPMS","flags":"ab","id":"DF44AAB","pressure_kPa":452.5,"temperature_C":187.0,"mic":"CRC"} {"time":"2022-08-11 01:36:15","model":"Schrader","type":"TPMS","flags":"aa","id":"AB55552","pressure_kPa":432.5,"temperature_C":35.0,"mic":"CRC"} {"time":"2022-08-13 08:27:24","model":"Schrader","type":"TPMS","flags":"54","id":"5555553","pressure_kPa":425.0,"temperature_C":120.0,"mic":"CRC"} {"time":"2022-08-16 10:48:29","model":"Schrader","type":"TPMS","flags":"aa","id":"B552AAA","pressure_kPa":425.0,"temperature_C":123.0,"mic":"CRC"} (Note: IDs munged just in case they're sensitive). I can't speak to the quality of data -- for what it's worth I do live on a regional road with a high speed limit, so it's understandable there would be some hot tires. However theses could also just be poor quality sensors, bad signals, or bugs in rtl_433. Even aside from the obvious things like carrying around and using apps on a cell phone, it's amazing to realize how much information everyone leaks just going about their day. I've not investigated anything about how frequently or reliably these signals are sent, but it does seem feasible this could get used for vehicle presence detection or even short-range tracking. [0] https://github.com/merbanan/rtl_433 https://github.com/merbanan/rtl_433
- fomine3 4y agoI like contents about hacking on this blog. Recommend to check other posts.
- awaisraad 4y agoi am just amazed how much jobs were created by introducing this sensor in cars.
- m-p-3 4y agoNow that makes me wonder, would the Flipper Zero be able to capture that kind of data? I'll have to buy one someday..