Hacking your car’s multifunction display

attiny_mfa_switcher

[Steve] has an older third generation VW Golf, and as those who have owned one surely know, the beloved VR6 engine is wonderful but finicky. He says that the VR6 is particularly picky when it comes to oil temperature, so his daily routine involves hitting the MFA switch five times upon starting his car to bring up the oil temp in the display. This obviously gets old after awhile, so he rigged up a small circuit to do the switching for him.

He pulled the gauge cluster from the dash and then located the pins that correspond to the MFA display switch. Using an ATtiny12, he put together a small circuit that toggles the switch for him automatically each time he starts the car. Since his solution uses so few parts, he was easily able to tuck his creation behind the gauge cluster before reinstalling it.

Now each time he gets in his car, he is quickly greeted with the engine’s oil temp without having to fuss with his display.

27 thoughts on “Hacking your car’s multifunction display

    1. He hasn’t really messed with the cluster, he has messed with an input going to the cluster for the MFA. The DOT doesn’t care.

  1. Hello Andrew,
    this is my hack, and a oil cooler is already installed on a stock engine.

    the problem is that when the oil is cool (below 60°C) it builds to much pressure at high revs, so you drive it slow until 60°C are reached.

    Steve

    1. @Steve

      Elegant solution to a simple problem. Good job.

      If you didnt have an atiny laying around, I think a 555 timer could have been used in its place. But the part count may have gone up.

      I digress. Could you have tapped the oil temp feed and driven an LCD directly? Then you’d avoid ripping apart the dash which, I’m sure, wasn’t pleasant.

      1. “Ripping apart” the dash of a Golf 3 to get the gauge cluster out requires removing 4 screws, some plastic covers and takes less than 5 minutes if you know how to do it. Changing a tire is a harder job :)

    2. Maybe use a synthetic?
      Also have you checked the thermostat on the cooling system?
      Now if you could interface to the bus you could have it change to OT when it was under x an or over y :)

      1. vr´s are run only on fully synthetic oil, the problem comes from a very often defect oil pressure limiter.
        And with cold oil the pressure goes then up to 15bar or more on high revs, killing the chain what is tensioned with the oil pressure.

  2. On the Saturn Sky Redline I used to have, the fog lights would only come on with the headlights if you hit the foglight button – but the button is electronic and resets every time you turn off the car. But the car looks better with the fog lights on, so I always wanted them to default to on. I wanted to do something a long these lines to toggle it at startup, but never got around to it. Neat hack though!

      1. More specifically, fog lights are easily misaligned (if they are aligned at all) and therefore have a tendency to blind other drivers (both oncoming drivers and drivers ahead of you).

    1. Not sure about the rest of the world but here in Australia there is a ~$300 fine for using your fog lights when there is no fog. For exactly the reason shadyman said, they tend to blind oncoming drivers.

  3. interestingly, with so few components, and such an easy fix……why haven’t VW done this?

    Then again if they did, th board would be a stupid price!

    “Zat vill be 3000euro bitte!”

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