Brake (On/Off) suitable OSD gauge?

I want to log when I push the brakes during track runs, so I attached OBD-II metering via the brake light switch. Therefore I record just two values, "On" or "Off" which I have made a custom PID for.

But what gauge should I use for best displaying this "brakes On/Off"?
In the Torque app for example, I noticed there is a "gauge" for that, called "On/Off display", but I can´t see there is one in RC

Later I probably will see how much percent (%) brake I apply. A simple solution maybe would be a potentiometer attached on brake pedal?
Surely there must be lots of implementations on this out there, any advice will be appreciated.


  • You could make it percentage channel, and scale it so that on is 100% and off is 0%.
  • edited July 2021
    Yes, that was my plan if there is no OSD "On/Off LED" available like in the Torque app.

    And as mentioned earlier, please show examples on suitable sensor setups on brake pedal :)
  • A potentiometer attached to the brake pedal will probably provide inconsistent data.
    Brake systems operate on pressure, not position; what you really need is a pressure sensor somewhere in the hydraulic system. Many modern cars have pressure sensors already available in their master brake cylinders.

    Which car do you have?
    I had the same challenge setting up RC for my Subaru BRZ, and ended up finding how to read the brake pressure data from the car itself:
  • Thanks for input. My car is old, a 1975 Chevy Monza. No OBD at all 😀

    You can see a video here:

    I use a Swedish developed OBD-II box that converts analogue values to OBD-II data. I don't need that precise data from the brake system, but it would be nice to log some braking percentage instead of just on/off.

  • Oh, sweet!
    Yeah, you probably want to find a way to install a brake pressure sensor instead then.

    Since you're dealing with analog inputs, you might also consider making a RaceChrono BLE DIY device using Arduino instead of introducing an inefficient OBD-II protocol in the middle.
  • I'm using a device from here:

    Sorry, only in Swedish but you can see a schematic diagram on start page

  • @tinsfci Have to talked to the company about how to setup the brake? Usually the hardware companies know the best how to setup the sensors. I'm pretty sure they have done several setups like that.
  • Yes, I have talked to them. They´re very helpful, but have (for now) no sensors for brake reading. As pointed out by timurrr, brake pressure sensor would be the best way to go.
    But see this as a "poor-mans-project" thing, like go the DIY Arduino way.
    I imagined that there would be some other folks here that practice racing or attends trackdays and also have "non-OBD"-cars, that may had set up logging for braking.
  • edited July 2021
    I'm sure many people have done it for RaceChrono, these DIY sensors are rather popular amongst motorcyclists. I'd definitely wire up a brake pressure sensor, but obviously it takes some research on how to connect it. I haven't done it myself.
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