Why You Probably Shouldn’t DIY A Car Airbag

May 10, 2026 by Maya Posch 13 Comments

Car airbags are both a very simple concept and a marvel of engineering, replacing the bone-shattering impact of unforgiving plastic and steel with a relatively soft landing in a funky-smelling air cushion. This deceptively simple concept requires that the gas generator activates only when there is a crash and finishes filling the airbag in the milliseconds before the squishy human’s cranium with its soft filling attempts to occupy the same space as said airbag. This makes mad Aussie bloke [Turnah81]’s attempt at DIY-ing a car airbag a most daring proposition.

Rather than messing about with an IMU and microprocessors, he went low-tech with an inertial fuel cut-off switch. These are mechanical switches that hold a steel ball in place with a magnet until a sufficiently large force — like a crash — dislodges the ball and triggers an event. Usually, a switch like this cuts off the fuel pump.

After a bit of fun with a crash-test rig and the airbag of a salvaged steering wheel, a DIY airbag was assembled using a compressed-gas cylinder instead of the fancy gas generator, along with an electrically triggered valve. Here, you can already see why modern airbags use a gas generator, as it is simply far more compact.

For the bag itself, a pillow case was adapted, with the subsequent crash test — as pictured above — going about as well as you can imagine. After this, he tried a few improvements, like using a bin liner and detonating some fuel, but it seems that the gas generator is very hard to beat for producing a large amount of gas in very little time.

Meanwhile, the inertial cut-off switch turned out to be more than sufficient for this purpose, and it was also used to trigger the original airbag. Of course, with how cheap those off-the-shelf airbag units are and are tested to be fit for purpose, you’d never DIY them for actual use in a car unless you were stark raving mad.

Airbags have a checkered history. There are some places you shouldn’t try to save costs.

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TDR For Auto Diagnostics Done On The Cheap

May 4, 2026 by Zoe Skyforest 14 Comments

A time domain reflectometer (TDR) is a useful tool to have for finding faults in a wiring harness. However, they don’t come cheap, putting them out of reach for many shadetree mechanics that like to work on their own cars. However, [László SZŐKE] has been exploring a neat way to build a similar device on the cheap.

Typically, time domain reflectometry involves shooting a short electric pulse down a wire, and listening for how long it takes to bounce back. The time depends on the length of the wire, so it can be used to determine the location of a break in conductivity. Unfortunately, these pulses move so fast that very fast, very expensive hardware is needed to make these measurements.

[László’s] technique relies on lower-tech hardware. Instead of sending a very short pulse down a wire, his rig uses a cheap C-Media USB audio device to send a 4 kHz or 8 kHz sine wave instead. Then, by listening to the reflection and measuring the phase shift, it’s possible to detect the distance to the end of the wire (or a break along its length). Some supporting hardware is required for protection’s sake, and to tune the setup for measuring shorter or longer cabling. However, with some smart software processing, [László] states that it’s possible to measure down to 1 cm resolution.

The idea is that this setup could prove particularly useful for automotive troubleshooting. If you measure a wire and the device reports a length of 30 cm, when you know the wire stretches several meters into the engine bay… you know there’s a break around 30 cm from your measurement point.

There’s still plenty of work to be done – for now, [László] is working on a new prototype that should have better performance when testing shorter cables. Still, we love to see this sort of out-of-the-box thinking put towards a common troubleshooting task. If you’re doing fun signal analysis work of your own, don’t hesitate to light up the tipsline.

Repairing A Mercedes EQC 300 BEV Battery

April 22, 2026 by Maya Posch 15 Comments

When [OGS Mechanics] got a Mercedes EQC 300 battery-electric car in for repair, it was found to have a bit of a weird issue: after sitting in a garage for a while, its range on battery had suddenly reduced significantly without clear cause. Although the typical response here is to just mark the battery pack as ‘faulty’ and replace the whole unit, [OGS] decided to dig into the pack to see what was going on.

The short version is that this particular battery pack consists of two individual batteries, each with its own BMS, one of which had reported a condition to the master BMS that triggered the ‘replace battery module’ error observed with the scan tool. From this it could also be seen that the first battery was at a 10% state-of-charge (SoC), and the second at 95%, making them incredibly unbalanced. Unfortunately the dealer procedure to rebalance did not work here, with only the second battery wanting to charge even after draining both to the same initial level.

To diagnose the underlying issue in earnest required gently prying open the battery pack like a massive glued-shut smartphone. Going by the theory that it is a software glitch, since the first battery was still at a healthy voltage level, it was decided to manually charge it. With both batteries now fully charged, the BMS for the first battery was then removed to have its memory overwritten with that of a known good BMS module, clearing the ‘replace battery module’ error.

Although in the preview for the next video it’s hinted that there’s also an internal balancing issue in the first battery pack, this could be another symptom of its BMS glitching out. Either way, it would seem that BEVs battery modules are both heavily dependent on software, as well as afflicted by the same throw-away culture that has people just buying a new smartphone when the battery fails.

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CAN Bus Analyzer Runs In Your Browser

April 21, 2026 by Zoe Skyforest 11 Comments

If you’ve got a modern car, truck, or tractor, it’s probably got a CAN bus or three that is bouncing data all around the vehicle. Listening in on these transmissions can enlighten you to what’s going on with sensors and modules which can aid in troubleshooting. You might find [Chanchal]’s latest work to be helpful in this regard — a CAN bus visualizer that runs right in your browser.

CANviz, as the project is known, is designed to work with any one of a number of cheap USB CAN reader modules. To use it, you simply run the Python “pip” tool to install it, and then you have a live CAN bus frame analyzer running on your local machine. Point your browser to localhost:8080 and you can see the data pouring in from whatever you happen to be hooked up to. The tool supports decoding CAN DBC files to make better sense of the raw data coming off the bus, and you can also record sessions for later analysis and even send CAN frames yourself if you need to. You can also run the tool on a remote single-board PC if so desired and access it over a network connection from another machine.

We’ve explored CAN hacking tools before and tools for visualization as well. Often, the latter is important when trying to debug and investigate dynamic issues. Meanwhile, if you’re working on your own automotive interface hacks, don’t hesitate to notify the tipsline!

Nissan Shuts Down NissanConnect App For Older Leaf EVs

April 8, 2026 by Maya Posch 66 Comments

Back in late February Nissan Leaf owners began to receive messages from Nissan informing them that the remote features in their cars would cease operation as the NissanConnect app would drop support for Leaf EVs produced before 2020 as well as eNV200 vehicles that were produced until 2022. The indicated cut-off date was March 30, giving affected users about a month to come to terms with the fact that their vehicle would soon to losing any and all remote control features.

What this highlights is an increasingly pertinent question when it comes to ‘connected cars’, which feature a built-in wireless modem to provide a range of additional features. These require access to a remote server for even simple remote features like controlling the charging process or turning on the heating. This has left many Leaf users rather dissatisfied.

While for such basic remote features you could make the argument that they’re just silly convenience features that do not affect the car’s functionality, modern cars are increasingly becoming reliant on such remote features, including for things like navigation and checking subscriptions for features like heated seats.

Increasingly it would seem that we’re looking at the Car-as-a-Service (CaaS) model being implemented.

Setting Up Tesla Model 3’s Computer For Bug Hunting

March 28, 2026 by Maya Posch 12 Comments

Like many high-tech companies Tesla runs a bug bounty program. But in the case of a car manufacturer, this means that you either already have one of their cars, are interested in buying one, or can gain access to its software-bits in another legal manner. Being a Tesla-less individual, yet with an interest in hunting bugs [David Schütz] thus decided to pursue the option of obtaining the required parts from crashed Tesla cars.

Specifically [David] was interested in the Tesla Model 3 and its combined Media Control Unit (MCU) and Autopilot computer (AAP) assembly. In addition to the main unit, it also requires – obviously – a power supply, and the proprietary display. These were all obtained fairly easily, but unfortunately the devices all had their cables cut off, leaving just a sad little stump of wiring with the still plugged-in connectors.

After trying his luck with an incompatible BMW LVDS cable from one of their headunit infotainment systems, he then proceeded to try and use the cable stumps with some creative patching. This briefly worked, but some debris fell onto the MCU board and blew a power rail IC.

Ultimately this IC got swapped after [David] had already purchased a whole new Model 3 computer, leaving him with two units and the easy way out of buying the Dashboard Wiring Harness cable loom that contained the Rosenberger connectors he needed to connect the display to the main unit.

A Voltage Regulator Before Electronics

March 16, 2026 by Jenny List 40 Comments

Did you ever wonder how the mechanical voltage regulator — that big black box wired up to the generator on a car from the ’60s or before — worked? [Jonelsonster] has some answers.

For most people in 2026 an old car perhaps means one from the 20th century, now that vehicles from the 1990s and 2000s have become the beloved jalopies of sallow youths with a liking for older cars and a low budget. But even a 1990s vehicle is modern in terms of its technology, because a computer controls the show. It has electronic fuel injection (EFI), anti-lock braking system (ABS), closed loop emissions control, and the like.

Go back in time to the 1970s, and you’ll find minimal electronics in the average car. The ABS is gone, and the closest thing you might find to EFI is an electronic ignition where the points in the distributor have been replaced with a simple transistor. Perhaps an electronic voltage regulator on the alternator. Much earlier than that and everything was mechanical, be that the ignition, or that regulator.

The video below the break has a pair of units, it seems from 1940s tractors. They would have had a DC generator, a spinning coil with a commutator and brushes, in a magnetic field provided by another coil. These things weren’t particularly powerful by today’s standards and sometimes their charging could be a little lackluster, but they did work. We get to see how, as he lifts the lid off to reveal what look like a set of relays.

We’re shown the functions of each of the three coils with the aid of a lab power supply; we have a reverse current relay that disconnects the generator if the battery tries to power it, an over-current relay that disconnects the field coil if the current is too high, and an over-voltage relay that does the same for voltage. The regulating comes down to the magnetic characteristics, and while it’s crude, it does the job.

We remember European devices with two coils and no field terminal, but the principle is the same. There is never a dull moment when you own an all mechanical car.

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