The Hardware

DISCLAIMER - You do all this at YOUR OWN RISK. Everything you do, you are responsible for. Not Me.

Take:

• 1 x Volvo XC90, any flavour from the P2 range (2003 to 2014)
• 1 x Arduino Uno or your favourite clone thereof
• 1 x CAN BUS Shield based on the MCP2515 CAN bus controller - I'm using the CAN-BUS Shield v1.2 from Seeed, but you can use whichever you like
• Some wire for the CAN bus - I chopped up a nice bright red Ethernet cable to use, but you can use anything
• A laptop of any flavour so you can run the Arduino IDE
• Some Arduino source code.
• A decent but simple serial logger like Realterm

Special Notes:

• Volvo P2 cars use 29-bit device IDs on the CAN bus
• The low speed CAN bus runs at 125kbps
• The CAN bus is a twisted-pair, white and green, and runs throughout the Volvo nearly to every device
• CAN-L is the green wire in the Volvo
• CAN-H is the white wire in the Volvo

Method (at your Desk):

• Install Arduino IDE on your laptop
• Install Arduino source code in the IDE
• Mount the CAN BUS shield to the Arduino
• Connect Arduino to a free USB port on the laptop
• Load the Arduino code into the Arduino
• Install Realterm on your laptop and make sure it sees the COM Port
• Make sure the Arduino initialises the CAN bus shield successfully
• Make sure Realterm sees the text output of the Arduino after Arduino reboot
• Study your Volvo wiring diagram and determine where you can best tap into the low-speed CAN bus on your car

Method (in your Garage)

• Connect the CAN bus shield to the CAN bus. You only need CAN-L and CAN-H, don't bother with Ground, +12V etc
• CAN-L is a green wire in the twisted-pair CAN bus in the Volvo
• CAN-H is a white wire in the twisted-pair CAN bus in the Volvo
• Plug in the Arduino to your laptop USB port
• Start Realterm
• Observe the bus magic!