2,5V CAN bus, but no data

Using Arduino Networking, Protocols, and Devices
#1

Short version:
Peuget partner: RX OK
BMW X3: NO RX LED

Hello! I am using a arduino Seeduino CAN bus shield V1.2. + OBDII-DB9 cable + BMW x3 2005 e83

I am getting data from my peugeot, but not from my bmw. I’ve tried both the 8Mhz and 16Mhz libraries, and measured the voltage in the bmw and peugeot, which seems normal, around 2.5V, and I’m pretty sure the bmw can bus should be working. (Going to test this more thoroughly)

Given that the RX led on the shield is lighting up when it receives data without any programming on the arduino board, leads me to believe the problem is not in my code or wiring. (Given that i have 2,5V on the can bus terminals on the shield)

So i am left wondering if there could be some incompatibility between the MCP2515 and the can bus in the bmw? Anyone experienced not getting any RX light?

#2

Did you check that the BMW is providing CAN bus access on the OBD II? It wasn't mandatory at that time.

#3

pylon:
Did you check that the BMW is providing CAN bus access on the OBD II? It wasn't mandatory at that time.

I am pretty sure there should be a can bus there, since pin 6 and 14 have the correct can bus voltages. I have been googling like a maniac, but there is very little data on it to be found. Most people just struggle with a broken fuse..

I can't even find the correct bitrate for the can bus, though i think it is 500k, though this is not the problem, since i get no signals from the port at all.

Maybe bmw is filtering the can bus, requiring som form om input code before transmitting can data?

#4