Automotive cluster ?

[mlu30]

Hi everyone! This is my first time posting a question here.
I am working on automotive instrument clusters.
I need help figuring out the formula they use in the examples below. I can read the codes they use in the Eprom and see the "answer" on the digital display on the instrument cluster. I just can't figure out the formula.
ANY HELP WOULD BE GREATLY APPRECIATED!

5A 03 E2 03 47 00 = 25906 Miles
CF CF 87 00 78 00 = 3539 miles
81 CD 6B 02 D8 0F = 16153miles
71 52 00 00 DC 04 = 8 miles

[JosAH]

@mlu30
Are those all the samples you have? Isn't there a manual available somewhere? Are you able to sample, say, 1m, 2m, 4m ..., 0m? What is the meaning of those six bytes? Why six?

kind regards,

Jos

[mlu30]

Hi Jos!
Those are what I have now for samples, as for a manual, I wish there was one. When you referred to sampling 1m, 2m, 3m etc I'm assuming your talking about 1 mile, 2miles, 3miles etc. I guess if I started with 1 and put a mile on and read it every mile, I probably could. Don't know what the meaning of the bytes are other then the answer (miles). You asked why 6, I don't know. Some other clusters use 2 bytes others use 5. I've tried all the formula's I know and none of them work.
Thanks for looking and taking the time to help!
Mike

[JosAH]

A very ignorant question for you: what are automotive instrument clusters? Do you actually have to move something to get another miles score? Do these things also measure fractions of miles?

kind regards,

Jos

[mlu30]

Hi!
In your car or truck, what ever you drive, you have on your dashboard,normally in front of your steering wheel, a instrument cluster were you can see your RPM, OIL pressure, Water temp and your Mileage.

[JosAH]

@mlu30
Ah, ok, thanks; I never knew what all these things right in front of me were called in English ;-)

Is the total milage a linear function of the total wheel rotations or is it more advanced? (e.g. rotations of the engine and the gear).

kind regards,

Jos

[mlu30]

Hi! Not sure about your last question

[JosAH]

@mlu30
Suppose the circumpherence of a wheel is 'x' metres then it has to rotate 1000/x times to make the car travel a kilometre (I'm metric ;-)

I was just thinking: do those bytes represent that 1000/x number or do those bytes represent something else, e.g. the number of rotations of the engine and the gear number.

I've played a bit with those bytes and I suspect that those six bytes represent two or more numbers; I haven't found anything interesting yet ;-)

kind regards,

Jos

[RedSon]

What is the make and model year of the vehicle? What can you tell us about the on board computer? What is the model or version of it's software? What software does it have on it? Is it an after-market eeprom? Are you reading this data off the CAN bus? Are you getting codes from the OBD system?

Do you have any consecutive numbers what is the data for when the car has 10 miles on it? 11? 12? 13?

[kadghar]

I tried several things with this numbers... i dont think it's a linear function or something easy to get.
I did made some research about EPROMS, and found here. It says that they must be erased in order to rewrite them, and that you need UV light at a frecuency of 253.7 (whatever that means) to do it.

So, wouldn't it be possible that this bytes are some kind of serial numbers, and there's not such thing as a formula, but a database?

[Dormilich]

@kadghar
it's not the frequency, but the wavelength (in nm). That's UV-C (Far UV) if that tells you more.