By on November 15, 2012

After I photographed today’s Junkyard Find in a Colorado self-service wrecking yard, I agonized over that digital instrument cluster. I have this crazy idea that I can hack old digital instrument clusters and operate them with an Arduino microcontroller, so that I can have a display on my office wall to go with my collection of weird diecast toy cars. It started out innocently enough, with this 1983 Mitsubishi Cordia cluster, and then I got the digital cluster out of a 50th Anniversary Nissan 300ZX. Once you have two 1980s Japanese digital dashes, you have a problem collection, right? That was my logic when I bought the digital dash out of this 1984 Toyota Cressida. Even though I’m getting too ambitious with this Arduino-ized-digital-dash project, I felt I had no choice but to go back the next day and grab the XT Turbo’s cluster. So I did.
Someone had already torn up the driver’s-side door-latch mechanism, so I had to climb in through the passenger side and dismantle the latches enough to open the driver’s door.
That’s when I noticed this odd “Speed Alarm” feature, which used a key switch to lock the speed alarm in and out. Oh, Subaru, when did you lose your weirdness?
The instrument cluster in the XT moves up and down with the tilt wheel, which adds immense complexity but is totally worth it for the coolness. It took me quite a while to figure out how to detach the cluster from this Rube Goldberg rig.
Toyotas and Hondas of this era are ridiculously easy when it comes to this kind of job; you can yank an 80s Civic or Corolla cluster in about 25 seconds with just a screwdriver. Subaru had a different philosophy, and so I started removing every 10mm and 12mm fastener I could find.
There’s a hinged bezel above the cluster that resisted all attempts to release the cluster (I could have just smashed the hell out of everything in the way, but I do my best to leave all the parts I don’t want in usable condition for the next parts shopper), and the connectors on the dash harness were fiendishly inaccessible and frozen solid (Subaru went with a much cheaper electrical-parts supplier than did Honda, Toyota, or even Mitsubishi). In the 35-degree weather of a November morning in Denver, my hands took a real beating during the cluster-removal process.
Leaking a little of the red stuff is no big deal, however, when your struggles end with a beautiful 1980s Japanese digital cluster for your collection.
While I was shopping, I also picked up a nice Weber DGV 32/36 carburetor from a car with a strange-yet-familiar engine swap. More on that in a future Junkyard Find!

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26 Comments on “Don’t Try This At Home: How Could Anyone Resist a Subaru XT Turbo Digital Dash?...”

  • avatar
    schmitt trigger

    Correct me if I’m wrong, but back then there was no CANBUS, but rather there were several proprietary digital busses. The challenge will be to find the proper interface circuit between the dashboard and the microcontroller of your choice.
    With CANBUS, there are many off the shelf solutions.

    • 0 avatar

      I believe all the analog to digital processing occurred in the cluster itself. Sensors on cars of that vintage are 0-5v or 12v pulses. Feed the right wire with the right signal, and digital graphics will get spit out of the black box.

      • 0 avatar

        You’re likely right about this. Definitely not gonna be a CANbus or any kind ISO protocol, just analog inputs. With the factory manual, Murilee should be albe to figure it out quite easily.

      • 0 avatar

        Feds, Exactly. These may look complicated, but they are really simple devices when it comes to their inputs. Though not nearly the ambitious project the author envisions, I had a couple of digital dashes hanging on the shop wall 8 or 10 years ago. But I just drove them with a Megastim since I had an extra floating around and it was easy.

    • 0 avatar

      I’m going to bypass all the clusters’ control circuitry and just control the LCD panels (all these things use LCD panels with light bulbs and colored plastic filters behind them) directly from the Arduino module. You can get some pretty cheap add-on kits for controlling big LED grids, and they should work with LCDs as well. This will require a lot of very finicky soldering of wires onto PCBs, but means I won’t have to engineer a way to spoof the tach signal, etc.

      Now I just need to brush up on the C++ I tried not to absorb as a software tech writer (if a tech writer can do code, that’s what The Man will make him do until This Very Important Ship Date is met, i.e. all the time), so I can write the code that will control my Wall Of 80s Japanese Digital Dashes after I’m done soldering 900 tiny wires.

      • 0 avatar

        Just kinda depends on what you want your end result to be able to “do”, but to me spoofing inputs to an otherwise functional discrete device is far more straight forward than messing with individual elements.

        Just depends on what you’re looking to do.

      • 0 avatar

        This digital cluster wall need to interface to an Ipod dock so the tachs pulsate to the beat and the speedos display track time.

      • 0 avatar


        Awesome idea.

      • 0 avatar

        Don’t know if I have mentioned this before, but I would use a Teensy before an arduino ( ), more pins, smaller size, same software (uses the arduino ide).

        My gut feeling, is to emulate the inputs as the others have said. Soldering all the leds/lights will be a bigger pain, and driving them won’t be much easier.

      • 0 avatar

        Whenever I’m Arduino-ing, I prefer to just use C and the avr-libc libraries rather than the actual Arduino C++ stack.

    • 0 avatar
      Athos Nobile

      I discovered that even Matlab has a section to simulate CANBUS.

      Actually, that would be a nice project, run the dash through the Arduino using Matlab.

      One of my uni lecturers was delighted when I forwarded one of MM’s links this semester.

  • avatar

    Oh, I feel for you in that cold. My skinny fingers lose heat very efficiently.

    How did I miss the post about the diecast model cars? I love them.

  • avatar

    Some poor archeologist is going to dig up your playroom with these bizarre out of context artifacts. Then proceed to write his doctoral thesis on the early 21st century mating rituals.

  • avatar

    Didn’t Japanese cars have some kind of required speed alarm? I’m guessing Subaru just put in a switch to disable it for the US market.

  • avatar

    Murilee–Haven’t you run out of space for all your toys yet? Do we intervene and send the “buried alive” hoarders team to your house?

    I do enjoy your posts, though, as an avid junkyard customer when I have the need. As I drive a bomber, I do have needs (glove box door release for a GM N-body).

    I do find myself running out of garage space. Some got trashed–does anybody really need a collection of auto seat belt controllers for early 2nd generation Camry’s? Or a collection of fwd GM A-body radiator caps? The wife won’t let that stuff move inside.

    • 0 avatar

      My wife often accuses me of being a car parts hoarder because of the amount of automotive goodness stacked up in the shop.

      I refuse to admit this based on the fact that the inventory rotates. Hoarders don’t sell or trade their junk!

      • 0 avatar

        I concur. My hobby/part time profession is selling random stuff on eBay. Some remark that I have a staggering array of weird junk around my house, but I note that it’s constantly different junk, never the SAME junk. Why else would someone have seven chainsaws and two identical Miatas?

    • 0 avatar

      I’m actually a pretty serious anti-hoarder in general, mostly because I had to move 13 times during the 1990s. I make allowances for small stuff (like weird diecast cars) and for bits intended for projects I have a reasonably good chance of completing, but I get freaked out if too much crap builds up. In my case, the real problem is books– I read a lot, I get rid of any book I probably won’t read again, but I still have more books than shelf space. Time for another Great Purge of reading material!

  • avatar

    When I was 12 we lived a block away from a Ford dealership. I would dumpster dive behind the service department and find all kinds of parts. I pretty much had the dash and controls for a car setup in the garage. Dad hated hoarding, so it didnt last long.

  • avatar

    Weber carbs … I still remember trying to tune a 40 DCOE. A glorious carb but I never did get it running quite right!

    • 0 avatar

      It’s a carb. One can only make it “right” if it runs in a static environment indoors – as a generator engine, and even then they still aren’t nearly as efficient as mechanical FI. The second temp, humidity, baro pressure, engine temp, throttle-position, or anything else changes, a carb ain’t “right” no more. Perhaps in the ballpark if you work really hard, but never even close to optimal.

      Carbs are for paperweights, or melting down into intake runners. They had no legit car use post 1973 save that they were cheap because the tooling was amortized. The McD’s of fuel delivery..

  • avatar

    I think the early 90’s maxima had one of the best digital dashboard

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