TunerPro User Forum

I've been trying to find a tool to calculate the correct checksum for my modified BMW M70 DME rom. It was sold to me by a German tuner, and the checksum was not corrected (early EU 850i models do not come with a check engine bulb in the dash as US cars do, so it was not deemed necessary).
My US car has the check engine light, and I can also read codes related to a checksum error.

If someone knows of a tool that will work for this ROM, or if you are able to make the checksum change if I email you the ROM, that would be awesome.

And I know there’s no such thing as a free lunch, so will compensate you for your time

Presumably your vehicle has two Motronic 1.7 ECU's in it and both will need the checksum correcting. There's a way of correcting the checksum given here (bit of a hack ), no idea if it works or not:

https://www.car-auto-repair.com/bosch-m ... de-winols/

Thanks for the link!
I'll check it out - and see if my brain can handle viewing the hex..

So I made it through the article, using the trial version of WinOLS (which I don't think I needed), and HxD.

The problem I had is that the checksum for the original .bin file is 1D8C, while the modified .bin is 0C4F

This means that to make the modified file's checksum match the original file using the subtraction method (i.e. zeroing out the FF values) I had to zero out a full 16 bit plus worth of values.

Despite this temporary head scratcher, the checksums now match, so I'll be able to burn and test when I can make it back down to my garage.

Thanks for the help!