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MQB-sniffer

CAN-BUS sniffing for Volkswagen Golf MK7 (and most likely other MQB platform cars). Currently this is more a work log for future reference.

Hardware used (not everything is required)

  • Car: VW Golf MK7, 2016, 2.0TDI (110kW, CRLB) + DSG (DQ250)
  • OBDeleven (GEN2) OBD2 adapter + iOS device + OBDeleven account with PRO license
  • ELM327 v1.5 (Carista)
  • MCP2515 + Arduino Nano + bunch of cables + PC/Mac/Linux
  • OBD2 cable splitter (to connect two OBD2 devices at the same time to the car)

Sniffing

Cables and adapters

  • OBD2 Splitter connected to the car
  • OBDeleven connected to one of the ports
  • Carista ELM327 connected to the other port
  • iOS device connected with OBDeleven adapter
  • Mac/PC/Linux connected with Carsita ELM327 dongle
  • serial monitor app running on Mac/PC, Carista ELM327 serial port connected at high baudrate (115200bps)

ELM327 config

Commands to send to Carista ELM327 to prepare it for data sniffing:

  • at z - reset ELM327 chip
  • at d - defaults
  • at sp 6 - set CAN-BUS to 11bit, 500kbps (Golf MK7 is using ISO 15765-4 CAN, 11 bit ID, 500 kbaud standard)
  • at cfc1 - flowcontrol
  • at d1 - show DLC
  • at al - enable long messages
  • at h1 - show headers
  • at caf0 - disable formating
  • at l0 - disable linefeeds
  • at s1 - enable whitespaces (easier to view data)

Data gathering

  • at ma - start sniffing
  • At the same time use OBDeleven to connect with car, go to list of modules, select module, select live data, select data type, view.
  • Carista ELM327 will sniff the communication between OBDeleven and car.

Injecting

ELM327 config

  • at z - reset ELM327 chip
  • at sp 6 - set CAN-BUS to 11bit, 500kbps
  • at al - enable long messages
  • at caf0 - disable formating
  • at v1 - enable frames shorter than 8 bytes (no padding)
  • at bi - bypass the initiation step

Sending frame

  • at sh 777 - set frame header to 777
  • 11 22 33 44 55 - send 0x11 0x22 0x33 0x44 0x55
    This will send this frame:
    Standard ID: 0x777 DLC: 5 Data: 0x11 0x22 0x33 0x44 0x55

Request headers and modules

Example data sniffed from OBDeleven-Car communication

Starting and maintaining communication with instrument cluster

714 8 02 10 03 55 55 55 55 55 - Accessing instrument cluster
77E 8 06 50 03 00 32 00 C8 AA - Cluster reply

714 8 03 19 02 AE 55 55 55 55
77E 8 03 59 02 19 AA AA AA AA

714 8 02 3E 00 55 55 55 55 55 - I'm here, don't sleep
77E 8 02 7E 00 AA AA AA AA AA - not sleeping!

714 8 02 3E 00 55 55 55 55 55
77E 8 02 7E 00 AA AA AA AA AA
...

RPM from instrument cluster

714 8 03 22 22 D1 55 55 55 55 - request
77E 8 05 62 22 D1 1F 98 AA AA - reply (0x1F98 = 8088 DEC; 8808 / 4 = 2022RPM)

Phototransistor instrument cluster (ambient light sensor)

714 8 03 22 22 4D 55 55 55 55 - request
77E 8 04 62 22 4D FA AA AA AA - reply (0xFA = 250 DEC; 250 out of 0-255 range; higher=brighter)

Enagaged gear from DSG

7E1 8 03 22 38 16 55 55 55 55 - request
7E9 8 04 62 38 16 00 AA AA AA - gear not engaged
7E9 8 04 62 38 16 0C AA AA AA - reverse
7E9 8 04 62 38 16 02 AA AA AA - 1st

Gearbox mode from DSG

7E1 8 03 22 38 15 55 55 55 55 - request
7E9 8 04 62 38 15 00 AA AA AA - P
7E9 8 04 62 38 15 01 AA AA AA - R
7E9 8 04 62 38 15 02 AA AA AA - N
7E9 8 04 62 38 15 03 AA AA AA - D
7E9 8 04 62 38 15 04 AA AA AA - S
7E9 8 04 62 38 15 05 AA AA AA - M

Warnings

  • Cheap ELM327 adapters will not work. Buffer will overflow with date before you can read the data from it.
  • For some reasons, when trying to use MCP2515 to sniff, experiencing communication problems between OBDeleven and the car. Tried both with and without EOL termination resistor with no luck.

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