Just for fun, I recently implemented something geeky and quite useful with my check-engine light (CEL), which is connected to an aux output on my ECU.
I don't have many gauges in the interior of my car, which is by choice, because I like the simplicity and lack of clutter. The only non-standard gauges I have are an Omori boost gauge and an oil pressure gauge.
I recently had an idea of how I could utilise the unlimited configurability of my e1280s Adaptronic ECU, and provide myself with heaps more engine-related data without installing any more gauges.
Firstly, I installed a small momentary push button next to the fog light switch and coin holder, below the ignition barrel. I wired this button to a digital input on my ECU.
I then added some completely custom functionality into my ECU, allowing me to use the push button to determine what the CEL does.
Currently I have the following behaviour implemented:
- Under normal conditions, the CEL will remain on or off depending on whether there are any engine problems. If I press the push button briefly, or restart the car, then the CEL will revert back to this 'normal' state.
- If I hold down the push button for a longer duration, there is a counter in the ECU which increments every 2 seconds, and the CEL will flash for about 0.6 seconds each time the counter increments.
- For each value of the incrementing counter, I assigned an important parameter in the ECU (I have noted this on a piece of paper in the glovebox, but I've memorised it anyway).
- After I choose a parameter that I'm interested in from the list, I then hold down the push button and count the flashes, releasing the button during the 0.6 second flash corresponding to the relevant parameter.
- The CEL will then begin a repeating cycle of flashes to tell me the value of the chosen parameter in the ECU.
- There is a 5 second gap between each repeating cycle, so if I get distracted it's easy to know when the start of the cycle is reached again.
- After the 5 second gap the CEL will flash the number of times corresponding to the counter value, so I can confirm that I chose the correct parameter (ie. that I held the button down for the correct duration).
- After the initial confirmation flashes, there will then be 3 separate groups of flashes to tell me the values of each digit in the parameter value (always treated as 3 digits).
- The number of flashes in each of the 3 groups, will be equal to the digit value + 1 (so a value of zero can still be interpreted).
As an example, I currently have '% Ethanol Concentration' assigned to parameter 1 for the CEL. Let's assume that the current ethanol concentration is 82%, ie. 0-8-2 when split into three digits.
Now, if I hold down the push button for 2 seconds and release it to choose parameter 1, then the CEL will continuously perform the following cycle until I reset the CEL back to the normal state:
[ 5 second gap -> 1 flash to confirm parameter 1 -> small gap -> 1 flash (1 + digit value 0) -> small gap -> 9 flashes (1 + digit value 8) -> small gap -> 3 flashes (1 + digit value 2) ] ... repeatingObviously this is no good for checking things on-the-fly like a proper gauge, but it's quick and easy to do when I stop the car.
Most importantly, I can access a huge amount of data (including things which can't be displayed on a gauge) with just one little check engine light!
I'll try to take a video of this soon :-)
post edited by robk - 2014/09/15 14:11:09