> Tesla offers a “Root access program” on their bug bounty program. Researchers who find at least one valid “rooting” vulnerability will receive a permanent SSH certificate for their own car, allowing them to log in as root and continue their research further.
Pretty interesting. Sounds like Apple's Security Research Device Program[0], where you're loaned a rooted iPhone, but with a clear qualification criteria.
It strikes a nice balance, because to qualify you have to 1) show you have the skills to get root access anyway and 2) show you're willing to participate in the bug bounty program and get things patched.
I would of course love root on everything I own, but I can understand Tesla's motivation here since root for everyone would make vulnerability discovery easier for malicious actors. And if everyone had root on their Tesla, it'd be much easier to make naughty modifications that might catch the ire of regulators. (like disabling driver attentiveness checks in self-driving mode).
Having shell is extremely handy for further discovery. SO handy that if they were just gonna patch the bug and lock you out, you would simply not disclose it.
I used to work for a company that made third party scan tools. We had racks of ecus disconnected from the car with just a diagnostic connector and power. nothing got to a real car without first trying it on the rack. I remember on time we figured out a bmw (pre obdii) had the bytes offset from the standard documentation (it was a semi-standard protocol that some other cars used at the time), we went from we communicate but nothing is wrong to a very long list of dtcs on that controller. (All our competitors also showed nothing wrong, but the official bmw tool showed dtcs)
I spent the last week successfully reverse engineering my car / various scan tools to get the right information to diagnose a fuel pump problem (and to do so without the incredible awkwardness of many of the tools)
It's pretty amazing what Claude + Ghidra + knowledgable coaching can accomplish. It was basically just setting direction, setting up an incremental workflow with the right kind of documentation, and questioning some of its theories and assumptions from time to time.
I'd love to release a lot of it but I'm torn between releasing artifacts created with expensive software I paid for and thinking that many of those things should really be freely available to anyone (specifically the things which definte the protocol to talk to the car and mapping of what various things are reported vs what they actually mean.
It's funny to hear LVDS be described as an "automotive" cable when all of my run-ins with it are for connecting laptop displays to their main-boards! (though that has a very different connector on it, and its a very general term for the signalling protocol from what I remember)
Not saying there's anything wrong with your perspective (lots of terms get in muddied waters, it's common and not a problem if everyone is on the same page), but this is what I just found on Wikipedia:
"Early on, the notebook computer and LCD vendors commonly used the term LVDS instead of FPD-Link when referring to their protocol, and the term LVDS has mistakenly become synonymous with Flat Panel Display Link in the video-display engineering vocabulary."
The cable in the article is pretty much doing the same conflation of terms that Wiki is talking about - the automotive one is a proprietary cable that carries some protocol that uses LVDS as its signalling, so at the most basic level both it and the display cable in the laptop are 'LVDS cables' but that's also the most generic term that gives you no information about the protocol actually being carried by the cables.
Yeah I saw that too which is why I posted my comment, it's surprising to me :) LVDS for display cables was an incredibly term in that context. Even still is sometimes despite them mostly being eDP (embedded-DisplayPort) now, which is quite incorrect hah
Most modern laptops no longer use LVDS for connecting the screen, but they use eDP (embedded DisplayPort).
So LVDS is more likely to linger in automotive displays, while in less obsolete devices it has been replaced by either eDP or by MIPI DSI (used e.g. in smartphones).
Very cool. Over a year and a half ago I installed a towing brake controller in my Tesla Model Y. Found the location of the plug, how to access and the pinout online (confirmed via a voltmeter..) so the car's side felt straight forward. But then I needed to find a brake controller that can work with the higher voltage (14.4v vs the normal 12v). Then built a cable from the brake controller to the connector that plugs into the car that I found on eBay. I velcro'd the controller under the dashboard. It works pretty well. I towed my small camper several times with it last year with no issues. Yay! However my little project is nothing compared to this post. Love people hacking away. So cool.
>then I needed to find a brake controller that can work with the higher voltage (14.4v vs the normal 12v)
Put a voltmeter on the battery terminals of a regular car at 2000rpm and note the voltage. You'd be surpised (the alternator can produce as high as 15V on some cars).
Automotive transients can be wild. I did a bringup with a board that had specified 100+v range specified for transients and finicky quality requirements on the output. The power supplies took up most of the (very large) board.
14v is not a transient, if your voltage was 12v with the car running, there's something wrong with the charging system (DC-to-DC in an EV, alternator/generator in an ICE)
13-14v is normal in all 12v automotive systems as the charging voltage
If I recall correctly, a fully charged lead acid battery has an open circuit voltage of 13.6V.
So the alternator has to put out at least something higher than if it’s planning on recharging the battery after 500 to 700 amps have been pulled from it for a few seconds to start the engine.
Yeah, max CV charging voltage is ~14V, max charging C rate is ~0.2C, open circuit voltage at 100% is that 13.x range. And lead acids like to stay at 100% unlike Li-ion which likes 50% +/-30%, so "12V" ICE cars just use a bus voltage of 13-14V and wire the battery there. At any given moment, the car's "12V" bus voltage MUST be above 13.x and below 14.4(absolute max).
It's a bit perplexing that those lead acid systems are referred to as "12V" systems when that figure is effectively the 0% voltage, whereas 3.7V for single Li-ion cell is the 50% voltage.
e: also, ICE transients can be in kV range, coming from ignition mechanisms. I've heard that you can literally measure engine RPM by selecting 1/dt on an oscilloscope and dividing that by cylinder count.
The nominal range for automotive systems is 10-16v. If you are designing anything for automotive use that doesn’t work reliably in that range, you are manufacturing problems for people.
I typically fault anything above 15.6V as “that’s a bit high, your alternator might be on its way out” when working on automotive / caravan / camper van appliances and accessories.
you're correct. a '12v ICE' alternator generates up to 14.8-15.2v. Most automotive stuff can operate between 9ish-16ish-v , of course totally depending on the product.
of course this is just a modern interpretation. older stuff runs at 6v and some weirdo offbeat cars have a 24v/48v rail sitting around somewhere. Cop cars often had alternators that put out weird voltage ranges for certain equipment, or dual 12v for high amperage output.
Even just a "12v" automotive battery itself is mostly dead if if actually reads 12.0V. Fully charged is around 12.6 or 12.7. If a car had an electrical system that actually ran at 12 volts, the battery would always be dead.
"12v" in reference to anything automotive is very much a nominal reference.
> Whilst cranking, an ICE car will drop to around 6 volts (then maximum power is extracted according to thevenim's theorem).
> That means all computers etc will work at 6v.
Not necessarily all of them. Plenty of stuff will drop out while cranking; hopefully not the computers that run the fuel injection and ignition, though.
The specs say no less than 6volts. In the real world when the temperature drops down to -70F or colder and batteries get old the voltage goes well below that: deal with it.
You are probably right. Surprisingly the first controller I tried didn't work. I assumed the voltage was too high since it worked in my other (much older) car. I found a reference online of people that tried a particular brand/model and that's what I went for. Thankfully my car isn't the model with the internal 18v battery.
This is awesome. Curious if these are plug and play and if that's the case where is the memory that tells you what the mileage is. If it's attached to the computer than the mileage would be off if you switch/repair it.
Completely unrelated. Would be interested if you figure out how to retrofit the new adaptive shocks on performance models to the older cars. Something I would love to do if I had hobby time. I'm pretty sure they fit physically, but needs to be connected to the main computer. I likely would never touch the main computer unless I got root access. In my brain I was thinking about a separate system made with raspberry pi's.
Hey, I just remembered my school used to have ages ago some cool power supplies (I think from Agilent?) that were very idiot proof, they had current limit with a dial that I think didn’t went over 1A or perhaps even less, and they would instantly disarm on short circuit (and indicate it with a led), and also the voltage dial I think wouldn’t go over 25V. I remember it was very big and heavy, but it survived countless students that used the lab daily.
Nowadays, is there any power supply available that is that resistant or is the recommended approach to get an used old one? Does anyone have a power supply at home that is also used by kids with a brand/model they would recommend? Thanks!
What you're describing is a lab power supply. (The "instantly disarm on short circuit" is overcurrent protection, which is a standard feature.) The name brands like Keysight or Rigol are kind of expensive, but there are a lot of no-name models on Amazon which will do the job well enough.
Congrats, OP has recreated a test/development bench, the bane of developers working on automotive software development all around the world. They're so close to being a real vehicle that you think you'll be able to get a lot of work done, but they're not, so you don't.
Honestly I love it. Few things develop a more fun camaraderie than a bringup bootcamp with two precious/priceless new samples on a large conference table, and everyone being very careful to keep cups/mugs very far away.
And a soldering robot with a specialist a few rooms away to beam down the latest errata into physical form, at times.
Tracy Kidder just died, and Soul of a New Machine was a favorite of my formative years as an engineer. Once I started in headunit ECU development it felt very familiar to me at times.
I'm a software guy, but the gear has a lot of allure.
That particular statement is also wrong. For this particular setup you can also buy the correct cable (making sure to not get the one that inverts some pins!!!) for cheaper. Mine was around 15$.
Violet HSD Code D 4+2 Pin Female to D Female Jack Connector 6 Pin HSD LVDS High Speed DataTransmission Harness Wire LVDS Cable
https://a.aliexpress.com/_EuGOh9e
> A REST-like API on :8080 which returned a history of “tasks”
I am curious to know what kind of historical tasks- since it's a media control unit; does it show what kind of media was being played in the last trip? does it reveal any other info about the driver?? There might be a privacy angle here that you could exploit and share it with Tesla.
They hit Odin. Odin is the diagnostic tool of Tesla.
The tasks they've seen are like "TEST_BRAKE_X_STIFFNESS-TEST-PRESSURE-BURNISHED" and are used to test different components of the car. They're also used for example to reset FSD strikes.
In Tesla terms, the infotainment does much more than just playing music - it has full access to the rest of the car.
People need to request the source code.. There’s a ton of open source they use that forces Tesla to give you source if you’re a customer and you ask. I don’t get why security people aren’t doing this already.
I _do_ find it weird that the LCDs from crashed cars are so expensive. I wonder if newer models have better screens, so people with older cars upgrade? Or if they're a common failure point?
I have a Model 3, but I can't say I follow the forums.. but I've never heard of screens failing -- I'm sure it happens but I think if it was common problem I'd have heard of it.
I'd guess they fail not on their own, but because they are human interface devices and take the brunt of abuse... e.g. iPhone screens are a popular repair despite being reliable components.
Some newer models have better (bigger) screens, and some are incompatible since they've slightly changed the connector. Old models (pre highland/ jupiter facelift) have used the same display shown in the article for a very long time across M3 and MY. What usually happens is that they physically break because people are not that careful, so the touch screen ends up breaking - although you really have to put a lot of force to break that display.
My 2016 Model S LCD panel developed the well-known fault of delamination and leaking some kind of sticky fluid.
Turns out the early Model S vehicles used consumer grade LCD panels that weren’t designed for the prolonged high heat you get in a metal and glass box left outside in the sun all day.
Tesla since upgraded their vehicle screens to proper automotive-grade LCDs which are excellent.
My point is, automotive-grade hardware is higher spec than regular consumer computer hardware, hence the high prices.
As an aside, I upgraded my whole computer and screen from MCU1 to MCU2 and it was worth the upgrade.
Credit to Tesla for building a retrofit computer upgrade for old vehicles. Thats a non-trivial thing to engineer and I appreciate their effort. Other car manufacturers would prefer you were compelled to buy their latest vehicle instead.
Ha! Reading this comment made me curious, so I went back and looked at the article and there does seem to be a full sized HDMI connector. I wonder if it is enabled, or just for Tesla internal testing?
Granted, I think it would be valuable to look at all sorts of automotive ECUs. I always wonder how the tuning industry does their thing; I shudder to think they're just sitting there flipping hex codes directly in running software...
i wish the ui on those things was more visually appealing. between the cheap looking gloss finish on the display itself and the unextraordinary ui, it's just kinda blah. one can have a debate about to screen or not to screen or whether to use vfd displays or whatever and i get the importance of cost control but it should look good and it really doesn't. the graphic of the car looks like a cartoon.
i think a lot of people do. i don't know what it is, there's maybe just something about the car graphic that doesn't sit right with me. the front/side view when parked just seems cheesy for some reason. maybe because it's meant to show unclosed doors or something and when everything is set the car's status is car which is redundant.
It does show open doors etc. but if not that then what would you show on the screen? You can already shrink it so the rightmost 3/4 of the screen is the map, leaving just 1/4 of the screen for the car visualization and indicators.
maybe it's the quasi-photorealistic nature of the car image that bothers me. it's not a photo, it's not a schematic, it's not a diagram. it's too artificial to look like a photo, yet too realistic to look like a schematic. or maybe the physically implausible lighting.
I'm amused reading the terms and requirements the author mentions in the bug bounty program for researchers gaining root access (under 'Vehicle Targets') - https://bugcrowd.com/engagements/tesla
"To promote further security research, Tesla offers security researchers the opportunity to retain root access on their infotainment system even after their reported vulnerability has been patched. In order to qualify, a researcher must send in a valid report describing a novel way to gain root access on a Tesla infotainment system. Upon confirmation, Tesla will instruct the researcher on how to use their existing root access to enable the researcher SSH feature, along with an SSH certificate for the researcher's public key (tailored to their specific hardware ID). The certificate restricts SSH access to the local diagnostic ethernet link. Tesla may renew the certificate as long as the researcher continues reporting vulnerabilities."
> Turns out that actual cars don’t have individual cables. Instead they have these big “looms”, which bundle many cables from a nearby area into a single harness. This is the reason why I could not find the individual cable earlier. They simply don’t manufacture it.
I was really surprised to read this at the end of the article -- how could someone be this deep into a project of this depth and not realize this?! Not only because all cars (...er... all vehicles) are wired this way, but also because the documentation they were referencing has plenty of detail to show this... there's even a whole picture of it (and to Tesla's credit they have amazing free docs): https://service.tesla.com/docs/Model3/ServiceManual/2024/en-...
Even if you know that cars consist of a single wiring harness, it's not implied that they aren't modular and the individual cables cannot be purchased separately.
Cars usually consist of multiple harnesses -- as it is in this case as well. The harnesses are the cables in a car. That is the part you can purchase because that is the part.
> and to Tesla's credit they have amazing free docs
Not to Tesla's credit, they had to be dragged kicking and screaming into it (primarily by Massachusetts) and their right to repair legislation through a solid chunk of malicious compliance:
1. When told that they had to have a site for people to order parts, Tesla put up a site that had every single item as "Call us", including the most simple of bolts. And when a few places called, "Sorry, that's not available to you".
2. The service manual was originally only available in a few locations in MA, and had strict conditions: you had to book in advance, there was a $100 fee per booking, and you could only view the manual on premises, and could not bring electronic devices into the room with you, just pen and paper.
The docs they have are great, and who knows how their attitude would have changed over time, but they absolutely didn't want you to have it, initially.
> The access story has been inconsistent over the years. Tesla has opened up free access to both the service manuals and diagnostic software in the past, but that was apparently a mistake, and loopholes were quickly closed.
"Always ... all free to use". Not so much.
And before that, even less available.
I will grant you for number 2, there seems to be some ambiguity - some people claimed it was only if you needed to actually use their diagnostic tools, because Tesla wouldn't sell them to anyone at the time (which is also in contradiction to your "everything you need, all free, always").
> I was really surprised to read this at the end of the article -- how could someone be this deep into a project of this depth and not realize this?!
Usually, for most other vehicles, the connectors are either standardized (e.g. radios, ISO 10487 [1], high-current chargers by VG 96917) or the foundation plugs, sockets and re-pinning tools are readily available by the vehicle manufacturer or by aftermarket suppliers.
Tesla truly went out of their way to make the life of third parties (such as wire harness repair shops) more miserable here.
I will say I’m surprised how far apart the two boxes are in the car. I guess they’re not where I thought. I would assume they’re both up near the dash.
The passenger side kick panel or behind the glove box are two very common places for vehicle computers -- some cars have them under the hood, which I always thought was a bad idea.
My RAM truck with the Cummins diesel engine has the engine computer mounted on the engine block. You'd think the heat and exposure to the elements would make that a bad idea, but I suppose Cummins knows what they're doing.
Sounds alright until you realize after spilling a bunch of flower vases in the trunk (hatchback) that the computer has literally no case on it and immediately shorts out while driving. Or a passenger spills a drink in the rear seat cup holder.
There is now a recall notice to pull the back seat out to install a $5 plastic cover over the thing.
And yep, it’s the main computer for the car which controls the electronic transmission etc. Immediate full on engine-shuts-off at speed on the freeway and you require a flatbed to tow it away level of broken. I’m sure the engine ECU is in the engine bay, but holy hell what a surprise!
I had a car with an all wheel drive computer in a similar spot in the late 2000s.
I had a small crack in the rubber seal around my sunroof from parking outside in the elements. When it rained, water seeped in, made its way down the a-pillar, pooled under the seat, and fried the computer.
Expensive fix but I was able to drive it to the shop.
Hehe I was thinking about FCA/Stellantis vehicles when I wrote that. I know it works and there are components made to work in that environment but it always felt intuitively wrong to me. Especially when the other side of the firewall is a much better environment and not far away
It’s because when placed inside the engine bay, the large wiring harness is shorter, which is not only cheaper, but also shorter wiring helps with the consistency of electrical timing and reduces noise.
Yes they do. They can tolerate engine bay heat, but not exhaust heat. They are usually shielded from getting soaked.
Some Mazdas put the metal-cased engine computer in a plastic air box that feeds cold air from the front, to help ensure the engine computer stays cool enough.
In general, I believe the cooling airflow from the frontal air and the cooling fans keeps engine bay in check.
Yeah, on the Cummins the ECU is mounted on the intake side of the engine away from the exhaust and turbo and toward the front right under the fuel injection pump so it gets lots of cooling air.
This thread is interesting to me 'cause I'm also a software guy and recently took a job dealing with building fighter jets and the amount of engineering going into the wiring and computers on those things is insane. It's been a very interesting learning experience.
Tesla also went to a 48v wiring harness in some of their vehicles to allow them to power more equipment with less copper. It might be one reason why they use nonstandard connectors, so people don't attempt to hook 12v equipment to the system and also the higher voltages might require connectors rated for it.
Now they just have to take the next step and have everything in the vehicle running on PoE.
Software people tend to overestimate their knowledge of other disciplines, writing it off as "easy" or work beneath them. Being overpaid compared to your peers certainly doesn't help dispel this feeling. Some people have built entire careers around designing wire looms.
Consider whether this is an uncharitable comment --- someone with little expertise in a discipline has made a rookie mistake and didn't realize that the wires weren't produced individually.
Professionals overestimating their knowledge is a very common thing!
A professional scientist I know (tenured, professor) recruited me to set up a backtesting framework for a predictive finance model. When the results were not as they expected (this person does not work in finance and never has), they asked to see the code, then told me that claude had found a problem with the way some of the calculations were done (there was actually no problem), supplied the claude comments, and told me to change the code to match what they thought was correct. I did it anyway. Had they had more expertise in the domain (finance), they likely would have been able to leverage claude as a tool rather than inadvertently pursuing a very stupid mistake. Domain experts tend to doubt their ability to excel in other domains which is amplified by LLMs.
This sounds rather similar to the form of scientific fraud where you first create a conclusion, then invent/manipulate the data until it supports your conclusion.
Try working on a software project as a non-developer and see if you still respond so negatively to their sentiment. I can’t tell you how many times developers tried to arrogantly and dismissively explain design principles to me, as an experienced, degree-holding designer, because they skimmed a whole Tufte book at some point.
I was a developer for a decade before I went to school for design, so I’ve seen it from the other side. It’s not all bad: that overconfidence can lead people to tackle problems they’d abandon if they really understood the domain’s complexities. But often it presents like developers acting like their genius developer brain allows them to solve difficult problems in completely different fields with a few glib analogies and a few brief thought experiments.
I am surprised that they are surprised that car wiring diagrams are online. People wouldn't accept cars without online service manuals and schematics, and some states mandate them by law. I just looked up this subsystem for my car via my public library. https://appcontent.chiltonlibrary.com/chilton_images/Honda/E...
It actually stands for "lizard brain"... it is (or at least was) an Infineon Aurix control and monitoring microcontroller, they may have changed to a newer one.
From the article
> Tesla offers a “Root access program” on their bug bounty program. Researchers who find at least one valid “rooting” vulnerability will receive a permanent SSH certificate for their own car, allowing them to log in as root and continue their research further.
Pretty interesting. Sounds like Apple's Security Research Device Program[0], where you're loaned a rooted iPhone, but with a clear qualification criteria.
It strikes a nice balance, because to qualify you have to 1) show you have the skills to get root access anyway and 2) show you're willing to participate in the bug bounty program and get things patched.
I would of course love root on everything I own, but I can understand Tesla's motivation here since root for everyone would make vulnerability discovery easier for malicious actors. And if everyone had root on their Tesla, it'd be much easier to make naughty modifications that might catch the ire of regulators. (like disabling driver attentiveness checks in self-driving mode).
[0] https://security.apple.com/research-device/
Having shell is extremely handy for further discovery. SO handy that if they were just gonna patch the bug and lock you out, you would simply not disclose it.
I used to work for a company that made third party scan tools. We had racks of ecus disconnected from the car with just a diagnostic connector and power. nothing got to a real car without first trying it on the rack. I remember on time we figured out a bmw (pre obdii) had the bytes offset from the standard documentation (it was a semi-standard protocol that some other cars used at the time), we went from we communicate but nothing is wrong to a very long list of dtcs on that controller. (All our competitors also showed nothing wrong, but the official bmw tool showed dtcs)
Diagnostic Trouble Codes?
Yes.
I spent the last week successfully reverse engineering my car / various scan tools to get the right information to diagnose a fuel pump problem (and to do so without the incredible awkwardness of many of the tools)
It's pretty amazing what Claude + Ghidra + knowledgable coaching can accomplish. It was basically just setting direction, setting up an incremental workflow with the right kind of documentation, and questioning some of its theories and assumptions from time to time.
I'd love to release a lot of it but I'm torn between releasing artifacts created with expensive software I paid for and thinking that many of those things should really be freely available to anyone (specifically the things which definte the protocol to talk to the car and mapping of what various things are reported vs what they actually mean.
Wait, why wouldn’t you post it/ write it up?
It's funny to hear LVDS be described as an "automotive" cable when all of my run-ins with it are for connecting laptop displays to their main-boards! (though that has a very different connector on it, and its a very general term for the signalling protocol from what I remember)
Not saying there's anything wrong with your perspective (lots of terms get in muddied waters, it's common and not a problem if everyone is on the same page), but this is what I just found on Wikipedia:
"Early on, the notebook computer and LCD vendors commonly used the term LVDS instead of FPD-Link when referring to their protocol, and the term LVDS has mistakenly become synonymous with Flat Panel Display Link in the video-display engineering vocabulary."
https://en.wikipedia.org/wiki/Low-voltage_differential_signa...
The cable in the article is pretty much doing the same conflation of terms that Wiki is talking about - the automotive one is a proprietary cable that carries some protocol that uses LVDS as its signalling, so at the most basic level both it and the display cable in the laptop are 'LVDS cables' but that's also the most generic term that gives you no information about the protocol actually being carried by the cables.
Yeah I saw that too which is why I posted my comment, it's surprising to me :) LVDS for display cables was an incredibly term in that context. Even still is sometimes despite them mostly being eDP (embedded-DisplayPort) now, which is quite incorrect hah
Most modern laptops no longer use LVDS for connecting the screen, but they use eDP (embedded DisplayPort).
So LVDS is more likely to linger in automotive displays, while in less obsolete devices it has been replaced by either eDP or by MIPI DSI (used e.g. in smartphones).
SpaceWire is also just LVDS with an uber-minimal routing protocol. It runs on a lot of satellites.
You can run QtCar (the Qt-based app that Tesla uses for their UIs) on QEMU - if you have the firmware.
https://x.com/i/status/1722717318009041104
DM me if interested
I'm actually somewhat surprised the OS fully boots when it's not connected to the expected vehicle peripherals
Very cool. Over a year and a half ago I installed a towing brake controller in my Tesla Model Y. Found the location of the plug, how to access and the pinout online (confirmed via a voltmeter..) so the car's side felt straight forward. But then I needed to find a brake controller that can work with the higher voltage (14.4v vs the normal 12v). Then built a cable from the brake controller to the connector that plugs into the car that I found on eBay. I velcro'd the controller under the dashboard. It works pretty well. I towed my small camper several times with it last year with no issues. Yay! However my little project is nothing compared to this post. Love people hacking away. So cool.
>then I needed to find a brake controller that can work with the higher voltage (14.4v vs the normal 12v)
Put a voltmeter on the battery terminals of a regular car at 2000rpm and note the voltage. You'd be surpised (the alternator can produce as high as 15V on some cars).
Automotive transients can be wild. I did a bringup with a board that had specified 100+v range specified for transients and finicky quality requirements on the output. The power supplies took up most of the (very large) board.
14v is not a transient, if your voltage was 12v with the car running, there's something wrong with the charging system (DC-to-DC in an EV, alternator/generator in an ICE)
13-14v is normal in all 12v automotive systems as the charging voltage
If I recall correctly, a fully charged lead acid battery has an open circuit voltage of 13.6V.
So the alternator has to put out at least something higher than if it’s planning on recharging the battery after 500 to 700 amps have been pulled from it for a few seconds to start the engine.
Yeah, max CV charging voltage is ~14V, max charging C rate is ~0.2C, open circuit voltage at 100% is that 13.x range. And lead acids like to stay at 100% unlike Li-ion which likes 50% +/-30%, so "12V" ICE cars just use a bus voltage of 13-14V and wire the battery there. At any given moment, the car's "12V" bus voltage MUST be above 13.x and below 14.4(absolute max).
It's a bit perplexing that those lead acid systems are referred to as "12V" systems when that figure is effectively the 0% voltage, whereas 3.7V for single Li-ion cell is the 50% voltage.
e: also, ICE transients can be in kV range, coming from ignition mechanisms. I've heard that you can literally measure engine RPM by selecting 1/dt on an oscilloscope and dividing that by cylinder count.
The nominal range for automotive systems is 10-16v. If you are designing anything for automotive use that doesn’t work reliably in that range, you are manufacturing problems for people.
I typically fault anything above 15.6V as “that’s a bit high, your alternator might be on its way out” when working on automotive / caravan / camper van appliances and accessories.
> But then I needed to find a brake controller that can work with the higher voltage (14.4v vs the normal 12v)
Not understanding this sentence. Most running ICE vehicles product closer to that 14.4 than 12v. I think a standard controller would have worked fine?
you're correct. a '12v ICE' alternator generates up to 14.8-15.2v. Most automotive stuff can operate between 9ish-16ish-v , of course totally depending on the product.
of course this is just a modern interpretation. older stuff runs at 6v and some weirdo offbeat cars have a 24v/48v rail sitting around somewhere. Cop cars often had alternators that put out weird voltage ranges for certain equipment, or dual 12v for high amperage output.
Even just a "12v" automotive battery itself is mostly dead if if actually reads 12.0V. Fully charged is around 12.6 or 12.7. If a car had an electrical system that actually ran at 12 volts, the battery would always be dead.
"12v" in reference to anything automotive is very much a nominal reference.
Whilst cranking, an ICE car will drop to around 6 volts (then maximum power is extracted according to thevenim's theorem).
That means all computers etc will work at 6v.
> Whilst cranking, an ICE car will drop to around 6 volts (then maximum power is extracted according to thevenim's theorem).
> That means all computers etc will work at 6v.
Not necessarily all of them. Plenty of stuff will drop out while cranking; hopefully not the computers that run the fuel injection and ignition, though.
The specs say no less than 6volts. In the real world when the temperature drops down to -70F or colder and batteries get old the voltage goes well below that: deal with it.
You are probably right. Surprisingly the first controller I tried didn't work. I assumed the voltage was too high since it worked in my other (much older) car. I found a reference online of people that tried a particular brand/model and that's what I went for. Thankfully my car isn't the model with the internal 18v battery.
This is awesome. Curious if these are plug and play and if that's the case where is the memory that tells you what the mileage is. If it's attached to the computer than the mileage would be off if you switch/repair it.
Completely unrelated. Would be interested if you figure out how to retrofit the new adaptive shocks on performance models to the older cars. Something I would love to do if I had hobby time. I'm pretty sure they fit physically, but needs to be connected to the main computer. I likely would never touch the main computer unless I got root access. In my brain I was thinking about a separate system made with raspberry pi's.
Say what you will about Tesla, but from a hacking point of view this is some of the coolest things I’ve seen in a while!
> A DC power supply capable of providing 12V
Hey, I just remembered my school used to have ages ago some cool power supplies (I think from Agilent?) that were very idiot proof, they had current limit with a dial that I think didn’t went over 1A or perhaps even less, and they would instantly disarm on short circuit (and indicate it with a led), and also the voltage dial I think wouldn’t go over 25V. I remember it was very big and heavy, but it survived countless students that used the lab daily.
Nowadays, is there any power supply available that is that resistant or is the recommended approach to get an used old one? Does anyone have a power supply at home that is also used by kids with a brand/model they would recommend? Thanks!
What you're describing is a lab power supply. (The "instantly disarm on short circuit" is overcurrent protection, which is a standard feature.) The name brands like Keysight or Rigol are kind of expensive, but there are a lot of no-name models on Amazon which will do the job well enough.
Keysight == Hewlett-Packard Old School.
Got this for ~50$ a while ago. It works perfectly for this exact setup (Tesla MCU on a bench), tested it, and used it for a lot of other projects.
https://a.aliexpress.com/_EvT5Kog
Those were called something like desktop power supplies.
https://www.mouser.com/c/power/power-supplies/power-supplies...
AT $5k it better make me breakfast, too.
They have variable dc power supplies on amazon on the cheap.
If you want that sort of reliability it will probably go towards 100$.
Congrats, OP has recreated a test/development bench, the bane of developers working on automotive software development all around the world. They're so close to being a real vehicle that you think you'll be able to get a lot of work done, but they're not, so you don't.
Honestly I love it. Few things develop a more fun camaraderie than a bringup bootcamp with two precious/priceless new samples on a large conference table, and everyone being very careful to keep cups/mugs very far away.
And a soldering robot with a specialist a few rooms away to beam down the latest errata into physical form, at times.
Tracy Kidder just died, and Soul of a New Machine was a favorite of my formative years as an engineer. Once I started in headunit ECU development it felt very familiar to me at times.
I'm a software guy, but the gear has a lot of allure.
> Unfortunately I had no other choice but to buy this entire loom for 80 USD.
Fwiw, mine costs $450 from Ford. Also in the US we call this a wiring harness, with the loom being the material that goes over the wires
That particular statement is also wrong. For this particular setup you can also buy the correct cable (making sure to not get the one that inverts some pins!!!) for cheaper. Mine was around 15$.
Violet HSD Code D 4+2 Pin Female to D Female Jack Connector 6 Pin HSD LVDS High Speed DataTransmission Harness Wire LVDS Cable https://a.aliexpress.com/_EuGOh9e
Interesting.
> A REST-like API on :8080 which returned a history of “tasks”
I am curious to know what kind of historical tasks- since it's a media control unit; does it show what kind of media was being played in the last trip? does it reveal any other info about the driver?? There might be a privacy angle here that you could exploit and share it with Tesla.
They hit Odin. Odin is the diagnostic tool of Tesla. The tasks they've seen are like "TEST_BRAKE_X_STIFFNESS-TEST-PRESSURE-BURNISHED" and are used to test different components of the car. They're also used for example to reset FSD strikes.
In Tesla terms, the infotainment does much more than just playing music - it has full access to the rest of the car.
"tuner" almost certainly refers to a radio (think AM/FM/SiriusXM) tuner module
People need to request the source code.. There’s a ton of open source they use that forces Tesla to give you source if you’re a customer and you ask. I don’t get why security people aren’t doing this already.
I _do_ find it weird that the LCDs from crashed cars are so expensive. I wonder if newer models have better screens, so people with older cars upgrade? Or if they're a common failure point?
I have a Model 3, but I can't say I follow the forums.. but I've never heard of screens failing -- I'm sure it happens but I think if it was common problem I'd have heard of it.
I'd guess they fail not on their own, but because they are human interface devices and take the brunt of abuse... e.g. iPhone screens are a popular repair despite being reliable components.
Some newer models have better (bigger) screens, and some are incompatible since they've slightly changed the connector. Old models (pre highland/ jupiter facelift) have used the same display shown in the article for a very long time across M3 and MY. What usually happens is that they physically break because people are not that careful, so the touch screen ends up breaking - although you really have to put a lot of force to break that display.
My 2016 Model S LCD panel developed the well-known fault of delamination and leaking some kind of sticky fluid.
Turns out the early Model S vehicles used consumer grade LCD panels that weren’t designed for the prolonged high heat you get in a metal and glass box left outside in the sun all day.
Tesla since upgraded their vehicle screens to proper automotive-grade LCDs which are excellent.
My point is, automotive-grade hardware is higher spec than regular consumer computer hardware, hence the high prices.
As an aside, I upgraded my whole computer and screen from MCU1 to MCU2 and it was worth the upgrade.
Credit to Tesla for building a retrofit computer upgrade for old vehicles. Thats a non-trivial thing to engineer and I appreciate their effort. Other car manufacturers would prefer you were compelled to buy their latest vehicle instead.
I love that it has a standard RJ45 ethernet connector.
I thought I saw an HDMI connector, but maybe I was wrong.
Ha! Reading this comment made me curious, so I went back and looked at the article and there does seem to be a full sized HDMI connector. I wonder if it is enabled, or just for Tesla internal testing?
It's only a debug port and not actually HDMI signaling, unfortunately.
How many PoE adapters would it take to charge a Tesla?
Mostly depends on how fast you want to charge.
Nice read. I would LOVE for someone to dump the whole FSD AI/ML model and try to run it in simulator! That would be awesome!
Granted, I think it would be valuable to look at all sorts of automotive ECUs. I always wonder how the tuning industry does their thing; I shudder to think they're just sitting there flipping hex codes directly in running software...
I have no wheels and I must drift
i wish the ui on those things was more visually appealing. between the cheap looking gloss finish on the display itself and the unextraordinary ui, it's just kinda blah. one can have a debate about to screen or not to screen or whether to use vfd displays or whatever and i get the importance of cost control but it should look good and it really doesn't. the graphic of the car looks like a cartoon.
Interesting take–– I feel the total opposite; I love the UI.
i think a lot of people do. i don't know what it is, there's maybe just something about the car graphic that doesn't sit right with me. the front/side view when parked just seems cheesy for some reason. maybe because it's meant to show unclosed doors or something and when everything is set the car's status is car which is redundant.
It does show open doors etc. but if not that then what would you show on the screen? You can already shrink it so the rightmost 3/4 of the screen is the map, leaving just 1/4 of the screen for the car visualization and indicators.
maybe it's the quasi-photorealistic nature of the car image that bothers me. it's not a photo, it's not a schematic, it's not a diagram. it's too artificial to look like a photo, yet too realistic to look like a schematic. or maybe the physically implausible lighting.
It's glass...
Great project. This begs for real-world feedback though. A go kart would be fantastic.
I'm amused reading the terms and requirements the author mentions in the bug bounty program for researchers gaining root access (under 'Vehicle Targets') - https://bugcrowd.com/engagements/tesla
"To promote further security research, Tesla offers security researchers the opportunity to retain root access on their infotainment system even after their reported vulnerability has been patched. In order to qualify, a researcher must send in a valid report describing a novel way to gain root access on a Tesla infotainment system. Upon confirmation, Tesla will instruct the researcher on how to use their existing root access to enable the researcher SSH feature, along with an SSH certificate for the researcher's public key (tailored to their specific hardware ID). The certificate restricts SSH access to the local diagnostic ethernet link. Tesla may renew the certificate as long as the researcher continues reporting vulnerabilities."
Very neat.
Really cool breakdown. You’ve got a full Tesla gaming rig now!
this is the coolest shi i've ever read on hackernews
> Turns out that actual cars don’t have individual cables. Instead they have these big “looms”, which bundle many cables from a nearby area into a single harness. This is the reason why I could not find the individual cable earlier. They simply don’t manufacture it.
I was really surprised to read this at the end of the article -- how could someone be this deep into a project of this depth and not realize this?! Not only because all cars (...er... all vehicles) are wired this way, but also because the documentation they were referencing has plenty of detail to show this... there's even a whole picture of it (and to Tesla's credit they have amazing free docs): https://service.tesla.com/docs/Model3/ServiceManual/2024/en-...
> how could someone be this deep into a project of this depth and not realize this
I think this is a software guy who occasionally dips into hardware things (to hunt bugs).
That's what I figure -- but it was wild to read that after reading the part about component-level PCB repair lol
Yeh, it seems odd to have the cut off cables, the wiring information...and then to go and buy a loom rather than bodging a cable at that point.
Even if you know that cars consist of a single wiring harness, it's not implied that they aren't modular and the individual cables cannot be purchased separately.
Cars usually consist of multiple harnesses -- as it is in this case as well. The harnesses are the cables in a car. That is the part you can purchase because that is the part.
There's a list of them here: https://service.tesla.com/docs/Model3/ServiceManual/2024/en-...
> and to Tesla's credit they have amazing free docs
Not to Tesla's credit, they had to be dragged kicking and screaming into it (primarily by Massachusetts) and their right to repair legislation through a solid chunk of malicious compliance:
1. When told that they had to have a site for people to order parts, Tesla put up a site that had every single item as "Call us", including the most simple of bolts. And when a few places called, "Sorry, that's not available to you".
2. The service manual was originally only available in a few locations in MA, and had strict conditions: you had to book in advance, there was a $100 fee per booking, and you could only view the manual on premises, and could not bring electronic devices into the room with you, just pen and paper.
The docs they have are great, and who knows how their attitude would have changed over time, but they absolutely didn't want you to have it, initially.
Tesla treated the service manual like congress treats certain recently surfaced files.
Wrong. They’ve always been open, even with their patents too. All free to use, no royalties
Confidently incorrect.
https://www.reddit.com/r/teslamotors/comments/utivlj/tesla_s...
> This used to cost $3187.50
https://driveteslacanada.ca/news/tesla-service-manuals-free-...
> The access story has been inconsistent over the years. Tesla has opened up free access to both the service manuals and diagnostic software in the past, but that was apparently a mistake, and loopholes were quickly closed.
https://www.teslaownersonline.com/threads/tesla-service-manu...
"Always ... all free to use". Not so much. And before that, even less available.
I will grant you for number 2, there seems to be some ambiguity - some people claimed it was only if you needed to actually use their diagnostic tools, because Tesla wouldn't sell them to anyone at the time (which is also in contradiction to your "everything you need, all free, always").
> I was really surprised to read this at the end of the article -- how could someone be this deep into a project of this depth and not realize this?!
Usually, for most other vehicles, the connectors are either standardized (e.g. radios, ISO 10487 [1], high-current chargers by VG 96917) or the foundation plugs, sockets and re-pinning tools are readily available by the vehicle manufacturer or by aftermarket suppliers.
Tesla truly went out of their way to make the life of third parties (such as wire harness repair shops) more miserable here.
[1] https://de.wikipedia.org/wiki/ISO_10487
I will say I’m surprised how far apart the two boxes are in the car. I guess they’re not where I thought. I would assume they’re both up near the dash.
The passenger side kick panel or behind the glove box are two very common places for vehicle computers -- some cars have them under the hood, which I always thought was a bad idea.
My RAM truck with the Cummins diesel engine has the engine computer mounted on the engine block. You'd think the heat and exposure to the elements would make that a bad idea, but I suppose Cummins knows what they're doing.
My car has it under the passenger seat.
Sounds alright until you realize after spilling a bunch of flower vases in the trunk (hatchback) that the computer has literally no case on it and immediately shorts out while driving. Or a passenger spills a drink in the rear seat cup holder.
There is now a recall notice to pull the back seat out to install a $5 plastic cover over the thing.
And yep, it’s the main computer for the car which controls the electronic transmission etc. Immediate full on engine-shuts-off at speed on the freeway and you require a flatbed to tow it away level of broken. I’m sure the engine ECU is in the engine bay, but holy hell what a surprise!
I had a car with an all wheel drive computer in a similar spot in the late 2000s.
I had a small crack in the rubber seal around my sunroof from parking outside in the elements. When it rained, water seeped in, made its way down the a-pillar, pooled under the seat, and fried the computer.
Expensive fix but I was able to drive it to the shop.
Hehe I was thinking about FCA/Stellantis vehicles when I wrote that. I know it works and there are components made to work in that environment but it always felt intuitively wrong to me. Especially when the other side of the firewall is a much better environment and not far away
It’s because when placed inside the engine bay, the large wiring harness is shorter, which is not only cheaper, but also shorter wiring helps with the consistency of electrical timing and reduces noise.
Could be because they sale crate engines.
Yes they do. They can tolerate engine bay heat, but not exhaust heat. They are usually shielded from getting soaked.
Some Mazdas put the metal-cased engine computer in a plastic air box that feeds cold air from the front, to help ensure the engine computer stays cool enough.
In general, I believe the cooling airflow from the frontal air and the cooling fans keeps engine bay in check.
For example, this is the board that’s used in Mazda CX-5 2017+ engine computers (mfr Denso), it lists max temperature range of +150C: https://www.renesas.com/en/document/mah/rh850e1l-users-manua...
Yeah, on the Cummins the ECU is mounted on the intake side of the engine away from the exhaust and turbo and toward the front right under the fuel injection pump so it gets lots of cooling air.
This thread is interesting to me 'cause I'm also a software guy and recently took a job dealing with building fighter jets and the amount of engineering going into the wiring and computers on those things is insane. It's been a very interesting learning experience.
If you'd like the cursed location for a vehicle computer, have the Smart fortwo's SAM. It's the fuse box!
It's also notorious for having awful solder connections and failing outright.
https://evilution.co.uk/mod/sam-unit-solder-repair.htm (and Aging Wheels: https://www.youtube.com/watch?v=n8AAleKR33Q)
EVS have actually managed to reduce the number of wire bundles (mostly due to switching to Ethernet instead of CAN Bus)
Tesla also went to a 48v wiring harness in some of their vehicles to allow them to power more equipment with less copper. It might be one reason why they use nonstandard connectors, so people don't attempt to hook 12v equipment to the system and also the higher voltages might require connectors rated for it.
Now they just have to take the next step and have everything in the vehicle running on PoE.
Software people tend to overestimate their knowledge of other disciplines, writing it off as "easy" or work beneath them. Being overpaid compared to your peers certainly doesn't help dispel this feeling. Some people have built entire careers around designing wire looms.
Consider whether this is an uncharitable comment --- someone with little expertise in a discipline has made a rookie mistake and didn't realize that the wires weren't produced individually.
Professionals overestimating their knowledge is a very common thing!
Fair, but software engineers are especially known for this. There was an XKCD about it
https://xkcd.com/1831/
> Software people tend to overestimate their knowledge of other disciplines, writing it off as "easy" or work beneath them
You should see what happens when someone involved in the sciences, e.g. Chemistry, gets their hands on Claude Code.
What happens?
A professional scientist I know (tenured, professor) recruited me to set up a backtesting framework for a predictive finance model. When the results were not as they expected (this person does not work in finance and never has), they asked to see the code, then told me that claude had found a problem with the way some of the calculations were done (there was actually no problem), supplied the claude comments, and told me to change the code to match what they thought was correct. I did it anyway. Had they had more expertise in the domain (finance), they likely would have been able to leverage claude as a tool rather than inadvertently pursuing a very stupid mistake. Domain experts tend to doubt their ability to excel in other domains which is amplified by LLMs.
This sounds rather similar to the form of scientific fraud where you first create a conclusion, then invent/manipulate the data until it supports your conclusion.
I work with a bunch of PHD's and have been since before ai coding.
Their code is aways terrible, and they constantly think it's good.
The exercise is always the same: explain the math to me, like I'm 5, then we profile it and see what is faster.
Oddly Claude Code, integrated into their IDE's has made this situation happen much less.
I never want to work in a place again where the fun way to start the Monday meeting is a "math problem".
PS: Don't even get me started on their SQL.
What a rancid comment. The first thing you can think of when seeing someone earnestly sharing their learning process, is to insult them of being vain.
Try working on a software project as a non-developer and see if you still respond so negatively to their sentiment. I can’t tell you how many times developers tried to arrogantly and dismissively explain design principles to me, as an experienced, degree-holding designer, because they skimmed a whole Tufte book at some point.
I was a developer for a decade before I went to school for design, so I’ve seen it from the other side. It’s not all bad: that overconfidence can lead people to tackle problems they’d abandon if they really understood the domain’s complexities. But often it presents like developers acting like their genius developer brain allows them to solve difficult problems in completely different fields with a few glib analogies and a few brief thought experiments.
He's right about the rest. We software people can definitely be annoying.
All people are annoying. It's still mean spirited in this instance. The author is likely reading all of these comments.
There's a reason that John Salvatier's 'Reality Has A Surprising Amount of Detail' blog entry is so evergreen on this forum.
It's called misplaced confidence and it isn't exclusive to software engineers. Doctors, engineers, presidents... The list goes on.
People tend to overestimate their knowledge of other disciplines.
I have worked with a LOT of PHD's in recent years. Their code leaves much to be desired.
I don't know, I've had more non-technical people and trades try and mansplain bullshit they don't understand than tech people have.
I'm sure you're an expert, pro at everything.
Yes I am. Thankyou for recognising that
I am surprised that they are surprised that car wiring diagrams are online. People wouldn't accept cars without online service manuals and schematics, and some states mandate them by law. I just looked up this subsystem for my car via my public library. https://appcontent.chiltonlibrary.com/chilton_images/Honda/E...
Could 'lb' be load balancer?!
It actually stands for "lizard brain"... it is (or at least was) an Infineon Aurix control and monitoring microcontroller, they may have changed to a newer one.
Fun linguistic quirk: Americans tend to call it a "wiring harness", whereas Brits prefer "loom"
As a result of this and the child comments…
As an Australian. I often find myself saying things like “the wiring hardness, or loom, or cable, or whatever were calling it this week”.
Exasperated by living in a state other than the one I grew up in. South Australians are often easily spotted by their pronunciation of certain words.
And, of course, Germans have a dedicated composite noun for it: Kabelbaum (literal translation: cable tree).
I always like to point out that Germans don’t, in fact, have a word for everything.
It’s just a phrase or sentence with spaces removed.
Knowhatimsayin.
In German that's called Wortbildungsfähigkeit, or in English, WordStructureCapability
So what do you call the tubing around the wire bundle? That’s what we call “loom”.
In Canada we generally call it the sleeve, or the wrap.
I'd understand either of those, but I'd go with "tubing"
https://www.3m.com/3M/en_US/p/c/electrical/wire-cable/tubing...
Very cool.
Now why didn't an AI think of that? :)