Hi guys,

Just thought Id ask and see if it was possible.. I want to see if I can modify the code for the trip computer. I dont like this stupid reset at 20hours and the intstant fuel economy doest adjust anywhere near as quick as I would like it to (compared to other cars Ive had). I want to be able to continue till I reset it or the battery is disconnected and to fiddle with the instant fuel economy update times.

Anyone tried before or attempted to read the code? Does anyone know what language its written in?

Cheers
Pete

Not yet, a microprocessor is most likely the brains behind it all, so an EPROM would store the program code. Problem is the data in the EEPROM is low level, lower then assembly, so it will be difficult if not impossible to deciper it and re-write a new one from it.

It may be possible however, to determine what microprocessor it is (Fingers crossed that its a Motorola 68HCxxxxx because I am familiar with that) and write a totally new code from scratch.

aaah your all a bit too 1337 for me here lol

Problem is the data in the EEPROM is low level, lower then assembly, so it will be difficult if not impossible to deciper it and re-write a new one from it.

Assembly code mnemonics have a one-to-one correlation with processor level op-codes so it should be easy enough to turn it back into assembly provided you can work out what processor you're dealing with. But that's the easy bit. lol

It's getting access to the code in the first place then finding a way to write it back that's going to stump you. Those sealed black box ECU things aren't meant to be tampered with by mortals.

hmmm yeah I wasnt too worried about deciphering the code, but I havent looked at what chip it is or anything, so no idea how hard it is gonna be to access it. I assumed they would have some sort of read/write protection, but didnt know how good it was...
I dont wanna write it all over again, as am happy with the rest, but just wanted to fine tune it.
Oh well I will have a look one day when I get the dash off again and see for myself.
Thanks guys
Pete

Yes re-writing code especially in assembly is a nightmare.

The code will definitely be housed in an EPROM chip, so you can easily create your own code and put it on a new EPROM chip (assuming the original EPROM doesn't have write permissions).

The other problem is that the trip computer is also the computer for the whole car that controls everything else, and it communicates to the ECU and Immoboliser module. Reading the communication channel between the BCM (Which we are referring to as the trip computer/Body Control Module) and ECU/Immobiliser won't help because it is most likely encryped.

Hmm, anyone know much about cryptography here? :badgrin:

I should also point out that the fact they put a limit on it probably means they've got a piddly small amount of memory to hold the data. Even if you could hack it to not reset at 20 hrs, you probably wouldn't have much more room to store fuel/distance/time data.