Custom Keyfob Fixes Mazda Design Mistake

While Mazda has made some incredible advances in fuel efficient gasoline engines over the past few years, their design group seems to have fallen asleep at the wheel in the meantime, specifically in regards to the modern keyfob design. The enormous size and buttons on the side rather than the face are contrary to what most people need in a keyfob: small size and buttons that don’t accidentally get pressed. Luckily, though, the PCB can be modified with some effort.

This particular keyfob has a relatively simple two-layer design which makes it easy to see where the connections are made. [Hack ‘n’ Tink] did not need the panic button or status LED which allowed him to simply cut away a section of the PCB, but changing the button layout was a little trickier. For that, buttons were soldered to existing leads on the face of the board using 30-gage magnet wire and silicone RTV. From there he simply needed to place the battery in its new location and 3D print the new enclosure.

The end result is a much smaller form factor keyfob with face buttons that are less likely to accidentally get pressed in a pocket. He also made sure that the battery and button relocation wouldn’t impact the antenna performance. It’s a much-needed improvement to a small but crucial part of the car; the only surprise is that a company that’s usually on point with technology and design would flop so badly on such a critical component.

Thanks to [Brian] for the tip!

59 thoughts on “Custom Keyfob Fixes Mazda Design Mistake

  1. Well done video and explanation. Two critical things I see with his new design:

    1) no tab to attach it to a keyring/your keys. But maybe he doesn’t need it?!
    2) the copper tape. It is fine for a while but oxidises quickly. That’s why I keep mine in a container with silica gel in it.
    This is especially true for damp climates and damp “local climates” like you jeans pockets can be in summer or after getting caught in the rain…

    But I guess he could get away with using a piece of the nickel plated strips he used for GND if the copper tape gets too “corroded” after some time…

      1. But do you think he went through all this trouble to make a keyfob for himself which might fail after a few months? I don’t think so. This IS his EDC keyfob now, so it should be made to withstand the everyday use of course…

    1. Hi Jan – Hank’n’Tink here (Brian). For number 1, yes – I don’t require (or want) a keyfob loop for other keys. Just my preference. I thought about mentioning in the video that a loop could easily be added to the 3D design, but thought the video was too long already.

      On #2, I’m not all that worried about oxidation, but am a little worried about galvanic corrosion of the dissimilar metals (copper and what I’m guess, but don’t know, is zinc on the battery). I’ve been using it for almost 6 months without issue, so I’m pretty happy so far… But really long term reliability remains to been seen. Easy to repair though, so I’m not worried.

  2. Great idea until the battery dies (which mine did) and then you need the physical key buried in the genuine Mazda key to open the door, pop the hood and jump the battery. With this design you are basically screwed.

    1. When you upload a video to YouTube, it asks you if it’s intended for children. It’s easy to misinterpret this as “would it be acceptable for children to see this?”, so it’s possible that the creator selected it, thinking the video was fine for children. It’s goofy, but I believe the creator can change this now, if desired.

    2. Hi – I’m the Hack’n’Tink guy. Sorry about that, it’s my first video post, and when asked if it was “Made for Kids”, I (wrongly) assumed that just meant “Safe for Kids”. I’ve now shut that off and commenting is restored.

  3. ‘It’s a much-needed improvement to a small but crucial part of the car; the only surprise is that a company that’s usually on point with technology and design would flop so badly on such a critical component’

    You’d be completely baffled by how many things slip through the net. I’ve worked with various high-end OEMs and some of their design decisions are truly bonkers. I imagine it happens in every industry to a certian extent, when you’ve got your nose against the coal face you don’t really think about what an actual customer might do or want and something so simple as “How does a person put the key in their pocket? Could they press the button accidentally?” might slip through that gap. It highlights the importance of systemic thinking and design.

    I hate how the automotive industry seems to be stuck in a lot of areas as people expect certain behaviour and a lot of things people don’t want to change as it “is the way they have always been done” This is really true on the switch to hybrid and EV, they have some behaviours which are holdovers from consequences of designs 50 years previously, and nobody wants to change it because people have an expectation on how it works.

    1. “people have an expectation on how it works.”

      This is the excuse for poor temperature control in brand new, modern ovens when a simple PID could keep an even heat, likely to a degree or a tenth. The recipes your grandma passed down wouldn’t bake the same! Bunk.

      1. It’d be trivial to have it both ways too. It’s not like they don’t put relatively advanced settings in appliances behind obscure menus.

        But it’s like they say in hockey…. Skate to where the puck WAS!

      2. What you’re talking about there is a unseen behaviour which 99% of people wouldn’t notice, so it’s a bit of a different issue. I think most people would like a more accurate oven, I know I certainly would.

        The excuse that an oven manufacturer would probably give is that mechanical temperature control is it works well enough for most people, is cheap, and has a small number of failure modes. They probably have the tooling for the part which has been the same for decades, so there really isn’t any reason for them to change. High end ovens probably do use PID or some other control mechanisms. I don’t know for certain as I haven’t designed a commercial oven, but those spring to mind.

        I’m talking more about things that have direct user feedback or interfacing like creep (how a car with an auto transmission behaves when you take your foot off the throttle), or the steering column controls. Loads of companies have played around with different mechanisms but a massive barrier to change it is simply “But people won’t like it because it’s different from other cars in the market.” mentality. And when they have changed things, the immediate negative feedback scares them into changing it back. (Or they just leave it and people just get used to it and it becomes a quirk of the brand.)

        There is also a difference between low, mid and high end vehicles. People who buy low to mid end cars “tend” to value shop, so they are more likely to switch brand to meet their needs / budget. (although they are likely to stay with a brand if it means a slight increase in price) so OEMs don’t like to change as it might be unattractive to customers. People who buy high-end vehicles “tend” to buy what they know, so when a high-end maker changes something usability related, people have an initial “What the F***” but after the next car they have already forgotten and have got used to the difference.

        This is mostly anecdotal experience from working in this area, but I haven’t studied it in detail. I just remember a lot of conversations when people have come up with new ideas to test and the first thing that comes out is “but my (insert car brand here) doesn’t do that”

        1. I’m learning to drive. I think this is most obvious when you’re new to a skill, because I keep having thoughts like “why do my hands have to leave the wheel for the turn signal”

        2. The trend these days to have “soft” buttons on a touch screen. Fair enough for some functions, but changing the radio station? Now I have to take my eyes off the road, re-focus onto the screen, search a significant portion of that screen for the right button, finger it (and note of if my press was detected), look back to the road… and at the brake lights of the car in front now two meters away because they decided to stop for a reason that was not even entirely clear to them!

          Old style radio… third button from the left… feel with my hand, feel the button press, station changed: and my eyes NEVER left the road, and I didn’t end up running smack-bang into that vehicle in front.

          Touch screens are all very nice – and cheap to implement – but sometimes a touch screen IS NOT what is the best solution.

          I suppose that is what it comes down to: safety takes a second seat to price.

          1. I’m just about to finish my studies to become an automation engineer (although I do have a fair bit of experience in that field since before) and I have had many arguments with my teachers about this. Yes, a touchscreen is great for some things but not all. Sometimes you just need the physical buttons for some reason.

            The same goes for internet connectivity. It might be good but just because you can connect a thing to the internet doesn’t necessary make that thing better.

          2. I can only hope that more engineers with common sense like you get into the places where you can show how stupid (and dangerous) some of the automotive industry decisions/designs are, and *hopefully* change them. It will very soon become… “oh, but that’s the way it’s always been done”…

    2. “is the way they have always been done” – A few decaded back I went to work in the Del Monte Foods IT group. The year I joined, the company was celebrating 100 years in business (not all that different from the auto industry at the time). The standard comment when exploring system designs – “We’ve always done it this way.” I still wonder what role that attitude played in the ultimate dismantling of the company – now just a brand name…

    3. All the remotes *without* a raised ring around the panic button so that when you do something like squat or bend over, sometimes just sitting down, pushes the button and off it goes. Then there’s the issue with the activation distance being longer than the de-activation distance, some times a lot longer. Ford is especially “good” at that one.

  4. The look and size of the keyfob design is subjective. Given the benefit of doubt that the Mazda design was indeed thought through carefully, it may be a case of Marketing trumps Engineering. Would it be something that helps sell the car and then the unsuspecting buyer has keyfob remorse after they have driven off the lot? Too bad.

    1. Simply putting the new key in the hand of anyone who’s had an old one will instantly tell you that the new one is a terrible design. The new one has no redeeming qualities. It is a complete failure.

    2. Engineers (hardware and software) are often too close to the project to see the problems. They *know how it works* and thus will not ever try to operate their thingus in any manner other than the way they’ve built or written it to operate.

      Then along comes Ordinary People and they hold the iPhone 4 like everyone who wasn’t an iPhone engineer did, with their right pinky finger or base of left thumb precisely bridging the antenna gap to short it out.

      Folding screen cellphone made with an essential layer to the display that looks just like the manufacturing and shipping peel off scratch guards common on electronic displays, nobody will ever try to peel that off, right? How many people instantly wrecked their first model of folding screen Samsung while applying their common sense experience with many other new devices?

      Usability design flaws often become “You’re holding it wrong.” or “It’s not intended to function that way.” before the manufacturer admits they goofed.

      Microsoft never admitted anything was done wrong, nor have they fixed, what was a stupid change from Windows 3.xx to Windows 95 when they put the Window Close button in 95 (and all subsequent versions) where the Window Maximize button was in 3.xx. 3.xx didn’t have a Windows Close button. Doubleclicking the Menu button in the upper left corner closed a window – safely far away from Minimize and Maximize. Instead of a Menu button, most programs now have a little icon in the upper left, but it functions the same as it did in 3.xx. Hitting Alt+F4 also closes a Window.

      So for some reason some folks at Microsoft decided there should be a single click way to close a window. OK, good idea, I guess. But then they got teh dumb and put it in the worst possible spot.

      EVERYONE who wasn’t starting out fresh with Windows 95 lost work at least once when they went to minimize a window and closed it. Microsoft decided that new users were more important and existing users would just have to get used to a period of high annoyance as they figured out all the “WTH did they change that for?” issues.

  5. The middle keyfob is Mitsubishi Electric, not Mazda. They just bought it/sourced it. I have one in my pocket, for my Mazda. It’s not always bad design choices, it could just be not reinventing the wheel when you are rushing to market.

  6. I think that Brian is likely not the customer they were designing for. In my experience, what customers need most is a key fob that they can find when they sit it down in a random place.

    If you are reading this blog, you are already far from the “average” customer.

    1. Size is an advantage when searching for a misplaced key fob. An even bigger advantage would be a distinctive color or pattern–yellow and violet stripes for example. The black and silver of the fob fails in this as well.

      1. Pink with purple stripes and yellow polka-dots. That’s what my dad always said when asked what color he was going to paint a car, a house, or anything else.

      1. Yes, true, I’m not an average car customer… But I’d expect I’m quite average for this site :-)

        (I an engineer, and I bet the number of engineers reading this blog is pretty high).

  7. Thank you, I needed to see this. I bought a new F250 and the fob is also ridiculously large.
    It’s so large I just leave it in the truck and use the Door pad to lock unlock or fumble with the app to remote start.
    What are these designers thinking? Do they imagine us wearing it like an amulet on a Run DMC chain?

    1. THAT is a very nice design. I have little doubt that IF a car manufacturer took notice, they could make it even thinner – having to work with the existing emergency key & PCB sizes/shapes very much limits what you can do.

      Hat off – nice work!

  8. Though in this case he was building a fob just for him, since he took time to compare the size of the other fobs it would have been nice to see his take on a 1:1 functional replacement including panic button and emergency key. Packaging constraints such as optional buttons and included keys are common reasons why designs seem larger than absolutely required.

    Of course his is also not waterproof or really drop resistant and I’d wonder how long it would hold up in a pocket full of keys anyway. But I can appreciate a home-brew individual solution to a problem.

    1. Yes – it was just for me. I would have done it regardless if other wanted to see it, but thought it might be record a video as I did it.

      Yes, it is most certainly not /designed/ to be water resistant or drop resistant. However, it is very light (just weighed it – 12g with battery) so I suspect it wound be reasonably drop resistant just because of it’s low mass and plastic case.

      A note on the panic button – the panic button just goes to another pin on the Atmel chip, and the chip internally decides to turn on panic mode if the button is held for ~3 seconds. Therefore, you COULD just attached the lock and panic buttons in parallel. In that case, a short press would lock, and a long press (~ 3 seconds) would panic. I tested this when I had it open on the bench. For me personally, though, I find panic a silly idea, so I scrapped it.

      About the LED, I kinda wish I did hook it up, because I realize now I hate the state when I’m trying to find my car in a parking lot by pressing the lock button. If there’s an LED, I can tell the difference between a dead-battery and being too far from my car. Haven’t replaced the battery yet, of course, but just saying…

      1. Sure and I can totally respect doing something that works for “just you”. That’s an interesting thought on the panic button.

        I modded a previous car’s keyfob as well, though in my case it was to enable some automation and just used transistors to replace the buttons. My current car has the remote built into the key but isn’t “keyless” just remote control, so it’s not particularly inconvenient. Though they ARE giant compared to a regular key’s body…

        1. Also on the matter of “just for you” – the whole premise of being able to buy a cheap 3D printer, mess with some free software, and you have a widget – is the driving force behind a lot of stuff that is now done. I would say the number of projects that ever make it to youtube (or to the web in any format) is actually quite low.

          I have several dozen (completed) projects that will never make it “to the ‘net”. My intent was to make something for me, and making a video/blog post about said widget is extra effort in an already-too-busy life.

  9. What kind of silicone RTV is that? The usual acetoxy cure stuff (which includes pretty much anything from an auto parts store) is corrosive thanks to the acetic acid produced during curing. Apparently that can help the gasket versions bond to metals by etching the surface, but it’s not so great for electronics. There are other chemistries that are more friendly to metals, but I haven’t run into easy places to buy them.

  10. Unfortunately my Mazda is old enough that a physical key is needed to start it. Like put it in the ignition and twist. The VW on the other hand, you have to pry off a cover to get to the one spot where a key can be used. (the VW is an EV, its very unlikely that the house battery will go flat, and if the fob battery dies, I would rob something else for its 2032. two options on my existing ring, plus a device I have to carry has a further two)

    As for the marketing thing, that could indeed be a real reason. They seem to think its important that the key feels substantial/impressive. A prior car (that had no remote control functionality) had a key with a big, thick. sculpted head, and an extended shaft. (and the head was just metal, no rfid, or such). It was supposed to say “luxury” . What it did do, was make it easier to break off and fit poorly on a conventional key ring. So I cut the head off, and brazed a small loop onto the extended shaft. Much better that way.

    1. Done very similar!

      Check no RFID (very important), smash plastic head off, drill hole in remaining metal, mount to keyring.

      Sits there like all my other keys – and like a damn key should!

  11. What about the other physical metal internal key for use if key battery has not enough power to unlock the car.Remove from fob and insert and unlock.Alarm goes off but stops when you start the engine.Get a new battery for fob.

    1. Simply use the existing hole on that key to mount it with your other keys. Using a key ring for turning leverage is better than trying to use the little tab from the key anyway.

  12. An automotive key WTH? from Ford for the 2007 to 2017 Expedition. For decades Fords (and other brands) had a pair of ‘wings’ or an extended, narrow, oval collar on the ignition lock so the driver could twist directly on the cylinder rather than the key itself.

    Then in 2007 Ford decides it’d be a great idea to go back in time to the 1950’s and make the face of the ignition lock plain and smooth so that all the twisting force must be done with the key.

    They also reverted the 3rd brake light to incandescent bulbs after having used LEDs in 3rd brake lights since the mid 1990’s on some models, like the Explorer and Mountaineer.

  13. Can you foresee any problems if I simply remove the panic alarm button. I’m thinking just snap it off with needle nose plyers. I constantly set it off bending down by my CX-5 with fob in my pocket.

    1. You can be virtually certain that removing the button is not an issue. Most all buttons for this kinds of device are normally-open momentary-contact buttons, and removing them has no affect to the circuit.

      The only issue I can see is that when physically snapping the button off the board – you do have to take a little bit of care, as there a possibility of pulling up traces on the PCB, or otherwise damaging the PCB. Best case would be to desolder it. But generally, no, it shouldn’t be a problem.

      1. Great thanks Brian, your video really helped me. I ended up just taking the fob apart and cutting the alarm button off, put a piece of electrical tape over the contact (looks better) and it works great. No more setting the alarm off while bending down by the car.

  14. Actually this is because the coil-shaped wire that runs from the rotating part of the steering wheel to the rest of the car is actually a somewhat tricky thing. It flexes hundreds of thousands of times during the car’s lifetime, and in a weird way. It is horrendously expensive to replace or service because it carries the control signals for the explosives in the airbag.

    Stuff like audio controls on the steering wheel are often wireless transmitters so they don’t add complexity to the coil wire. Safety-related functions like turn signaling might not be as easily switched over to wireless.

    So, that’s at least part of the reason why the turn signal stalk doesn’t rotate with the rest of the steering wheel.

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