Motronic

[Land Shark]

At 12:48 PM 1/16/97 -0800, you wrote:

>The only system I've ever explored previously was the older (pre-93) Weber
>Marelli ECU, as used on Ducati and Moto Guzzi motorcycles and (I've heard)
>Alfo Romeo 6 cylinder cars.  There wasn't any checksum problem at all, you
>could whack in any changes to the EPROM at will.  

 Older Motronic systems (pre 1987ish, pre DME M1.x) have no checksums
 whatsoever.. those are (example) on the E30 BMW M3, E28 535i, etc..

 Everything after 1987 (in the BMW world) has a checksum...

>Is the Motronic checksum
>just a loop that adds all the EPROM bytes together and compares that value
>to the checksum value?  (don't answer if that is sensitive information, I'm
>merely curious and not working on a Motronic system)

 Actually it can be ONE checksum or MULTIPLE checksums

 The Bosch Transmission computers (AEGS) use MULTIPLE INTERLEAVED checksums!

 Jim