Toyota Heater Switches Learn New Tricks

The look, the feel, the sound — there are few things more satisfying in this world than a nice switch. If you’re putting together a device that you plan on using frequently, outfitting it with high-quality switches is one of those things that’s worth the extra cost and effort.

So we understand completely why [STR-Alorman] went to such great lengths to get the aftermarket seat heaters he purchased working with the gorgeous switches Toyota used in the 2006 4Runner. That might not sound like the kind of thing that would involve reverse engineering hardware, creating a custom PCB, or writing a bit of code to tie it all together. But of course, when working on even a halfway modern automobile, it seems nothing is ever easy.

The process started with opening up the original Toyota switches and figuring out how they work. The six-pin units have a lot going on internally, with a toggle, a rheostat, and multiple lights packed into each one. Toyota has some pretty good documentation, but it still took some practical testing to distill it down into something a bit more manageable. The resulting KiCad symbol for the switch helps explain what’s happening inside, and [STR-Alorman] has provided a chart that attributes each detent on the knob with the measured resistance.

But understanding how the switches worked was only half the battle. The aftermarket seat heaters were only designed to work with simple toggles, so [STR-Alorman] had to develop a controller that could interface with the Toyota switches and convince the heaters to produce the desired result. The custom PCB hosts a Teensy 3.2 that reads the information from both the left and right seat switches, and uses that to control a pair of beefy MOSFETs. An interesting note here is the use of very slow pulse-width modulation (PWM) used to flip the state of the MOSFET due to the thermal inertia of the heater modules.

We love the effort [STR-Alorman] put into documenting this project, going as far as providing the Toyota part numbers for the switches and the appropriate center-console panel with the appropriate openings to accept them. It’s an excellent resource if you happen to own a 4Runner from this era, and a fascinating read for the rest of us.

Tech In Plain Sight: Windshield Frit

You probably see a frit every day and don’t even notice it. What is it? You know the black band around your car’s windshield? That’s a frit (which, by the way, can also mean ingredients used in making glass) or, sometimes, a frit band. What’s more, it probably fades out using a series of dots like a halftone image, right? Think that’s just for aesthetics? Think again.

Older windshields were not always attached firmly, leading to them popping out in accidents. At some point, though, the industry moved to polyurethane adhesives, which are superior when applied correctly. However, they often degrade from exposure to UV. That’s a problem with a windshield, which usually gets plenty of sunlight.

The answer is the frit, a ceramic-based baked-on enamel applied to both sides of the windshield’s edges, usually using silk screening. The inner part serves as a bonding point for the adhesive. However, the outer part blocks UV radiation from reaching the adhesive. Of course, it also hides the adhesive and any edges or wiring beneath it, too.

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Ask Hackaday: What’s Your “Tactical Tool” Threshold?

With few exceptions, every field has a pretty modest set of tools that would be considered the minimum for getting most jobs done. A carpenter can make do with tools that would fit in a smallish bag, while a mechanic can handle quite a few repairs with a simple set of socket wrenches and other tools. Even in electronics, a lot of repairs and projects can be tackled with little more than a couple of pairs of pliers, some cutters, and a cheap soldering iron.

But while the basic kit of tools for any job may be enough, there will always be those jobs that need more tools. Oh sure, sometimes you can — and should — make do with what you’ve got; I can’t count the number of times I’ve used an elastic band wrapped around the handles of a pair of needlenose pliers as an impromptu circuit board vise. But eventually, you’re going to come upon a situation where only the “real” tool will do, and substitutes need not apply.

As I look around my shop and my garage, I realize that I may have a problem with these “tactical tool” purchases. I’ve bought so many tools that I’ve used far fewer times than I thought I would, or perhaps even never used, that I’m beginning to wonder if I tackle projects just as an excuse to buy tools. Then again, some of my tactical purchases have ended up being far more useful than I ever intended, which has only reinforced my tendency toward tool collecting. So I thought I’d share a few of my experiences with tactical tools, and see how the community justifies tactical tool acquisitions.

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Take A Deep Dive Into A Commodity Automotive Radar Chip

When the automobile industry really began to take off in the 1930s, radar was barely in its infancy, and there was no reason to think something that complicated would ever make its way into the typical car. Yet here we stand less than 100 years later, and radar has been perfected and streamlined so much that an entire radar set can be built on a single chip, and commodity radar modules can be sprinkled all around the average vehicle.

Looking inside these modules is always fascinating, especially when your tour guide is [Shahriar Shahramian] of The Signal Path, as it is for this deep dive into an Infineon 24-GHz automotive radar module. The interesting bit here is the BGT24LTR11 Doppler radar ASIC that Infineon uses in the module, because, well, there’s really not much else on the board. The degree of integration is astonishing here, and [Shahriar]’s walk-through of the datasheet is excellent, as always.

Things get interesting once he gets the module under the microscope and into the X-ray machine, but really interesting once the RF ASIC is uncapped, at the 15:18 mark. The die shots of the silicon germanium chip are impressively clear, and the analysis of all the main circuit blocks — voltage-controlled oscillator, power amps, mixer,  LNAs — is clear and understandable. For our money, though, the best part is the look at the VCO circuit, which appears to use a bank of fuses to tune the tank inductor and keep the radar within a tight 250-Mz bandwidth, for regulatory reasons. We’d love to know more about the process used in the factory to do that bit.

This isn’t [Shahriar]’s first foray into automotive radar, of course — he looked at a 77-GHz FMCW car radar a while back. That one was bizarrely complicated, though, so there’s something more approachable about a commodity product like this.

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Saving Fuel With Advanced Sensors And An Arduino

When [Robot Cantina] isn’t busy tweaking the 420cc Big Block engine in their Honda Insight, they’re probably working on some other completely far out automotive atrocity. In the video below the break, you’ll see them take the concept of a ‘lean burn’ system from the Insight and graft hack it into their 1997 Saturn coupe.

What’s a lean burn system? Simply put, it tricks the car into burning less fuel when it’s cruising under a light load to improve the vehicle’s average mileage. The Saturn’s electronics aren’t sophisticated enough to implement a lean burn system simply, and so [Robot Cantina] did what any of us might have done: hacked it in with an Arduino.

The video does a wonderful job going into the details, but essentially by using an oxygen sensor with finer resolution (wide-band) and then outputting the appropriate narrow band signal to the ECU, [Robot Cantina] can fine tune the air/fuel ratio with nothing more than a potentiometer, and the car’s ECU is none the wiser. What were the results? Well… they weren’t as expected, which means more experimentation, more parts, and hopefully, more videos. We love seeing the scientific method put to fun use!

People are ever in the quest to try interesting new (and sometimes old) ideas, such as this hot rod hacked to run with a lawnmower carburetor.

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The Surprisingly Manual Process Of Building Automotive Wire Harnesses

Even from the very earliest days of the automobile age, cars and trucks have been hybrids of mechanical and electrical design. For every piston sliding up and down in a cylinder, there’s a spark plug that needs to be fired at just the right time to make the engine work, and stepping on the brake pedal had better cause the brake lights to come on at the same time hydraulic pressure pinches the wheel rotors between the brake pads.

Without electrical connections, a useful motor vehicle is a practical impossibility. Even long before electricity started becoming the fuel of choice for vehicles, the wires that connect the computers, sensors, actuators, and indicators needed to run a vehicle’s systems were getting more and more complicated by the year. After the engine and the frame, a car’s wiring and electronics are its third most expensive component, and it’s estimated that by 2030, fully half of the average vehicle’s cost will be locked in its electrical system, up from 30% in 2010.

Making sure all those signals get where they’re going, and doing so in a safe and reliable way is the job of a vehicle’s wire harnesses, the bundles of wires that seemingly occupy every possible area of a modern car. The design and manufacturing of wire harnesses is a complex process that relies on specialized software, a degree of automation, and a surprising amount of people-power.

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strut mounted on lathe

Turning Irregular Shapes

In case you’re not closely following Egyptian Machinist YouTube, you may have missed [Hydraulic House]. It’s gotten even harder to find him since he started posting under[بيت الهيدروليك]. Don’t let the Arabic put you off, he delivers it all in pantomime.

A recent drop is “How To Turn Irregular Shapes On The Lathe“.  We’re not sure, but think the part he’s working on is the front suspension of a  3 wheeled auto-rickshaw. The first metal at the center is over 30cm from the bottom. No problem, he just makes a long driven dead center from a bit of scrap material and goes on with his business.

By no means is this the only cool video.  We liked his video on a remote pumped hydraulic jack  and one on making your own hydraulic valves.

If you’re into machinist-y things, don’t miss him. Every video is full of pretty nifty tricks, sometimes made with a zany disregard of some basics like “maybe better to have done the welding before mounting in the lathe”, turning with a cutoff tool (I think), and occasionally letting go of the chuck key. It’s definitely ‘oh, get on with it’ machine shop work.

We love videos from professionals in the developing world making with relatively simple tools. Often hobby hackers are in the same position, milling with a lathe and some patience instead of a giant Okuma. Not long ago we posted this article about making helical parts , with the same ‘imagination and skill beats more machinery any day’ vibe.

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