shoulders

I have been messing with obdII and what i found is BMWs with the obdii socket inside definately have obdII and up until about 2000 - 2002 they used the ISO 9141 protocol (elm 323 will work with these), but newer BMWs are now using the CAN protocol.(you need elm 327 which supports all protocols)

For those BMWs that do not have the OBDii socket in the cabin they might still be obdII compatable. must be at least 1996 onwards, this is when it was made law in america so some european models might be compatable (mine is, 1997 318is coupe M44 engine, motronics ECU)(made law 2002 in europe to be compliant).

the way I checked it is to see if pin 17 is populated in the 20 pin DLC of the BMW connector(second K line), I believe it was a legal requirement to have a seperate line from the ECU to supply OBDII data. Diagrams lable this as TX II or a K line. Also check pin 2 this is sometimes label as OBDII line.

BMW call their diagnostic link the K line as well.

Where the 20 pin dlc has to be used with the ELM interphase you can buy a DB9 (serial type) plug to BMW 20 Pin DLC on EBAY.

Also i think a rule of thumb is later bosche motronic ECUs were compliant but the siemens ones were not ever.

All BMWs can be accessed by carsoft or BMW DIS (dealer software) but as you know only OBDii compliant ones accessed by OBDII interphase and software.

I have diagrams of the carsoft interphase and obdII cables if they are of any help.

As far as i know BMW do use a iso 9141 protocol to communicate to their own stuff but it is slightly different, i.e. the packets are slightly bigger so you can not use an OBDII interphase to get at BMW only stuff i.e. reprogramming the ECU or putting the windows up.