Measuring CAN BUS on Mercedes A W196

[omglol]

Hello!

I would like to see CAN bus signal on Mercedes A class W169, make year 2008 ... just for educational purposes. I connected ground on pin 5 of OBD connector and then I triend looking for the signal on pin 6 and pin 14 of OBD connector ... nothing appears on oscilloscope. :S If I connect it to pin 16 (+12V), I can normally see 12V voltage ... what am I doing wrong? I am measuring during engine running, of course ...

[smayer]

Try connect ground on pin 6 and look the signal
on pin 14.

[omglol]

Hmm ... very strange ... I now put diagnostic tester on and started diagnostic session, set to display current RPM of the engine ... and then I put probes on cable between OBD and diagnostic tester ... and CAN signal can be seen without problems! But as soon as I stop diagnostic session, the signal disappears ... how come?!

[omglol]

Does someone have wiring diagrams for this thing maybe? A-class, W169, make year 2008, 160CDI. Especially around OBD connector ...

[euror]

Why don't you locate the CAN Hi and Lo bus at other ECU, that's much more easy.