user17159: I recently bought a Sparkfun Can-Bus Shield, and tried the SparkFun_CAN_Demo from here but the program only prints "CAN-Bus Demo" and then does nothing, even when I have it connected into my vehicle's OBD-II port and the key is turned to ON (I can't run the engine because I am in my garage). Any help will be appreciated.

user23841: SPI pins are located on different pins in Arduino Mega. You have to wire it correctly with your shield. Some shields uses ICSP (6-pin header) for better compatibility but this one doesn't.
See Arduino SPI Reference for more details (section: Connections)

17159: <p>I recently bought a <a href="https://www.sparkfun.com/products/13262" rel="nofollow noreferrer">Sparkfun Can-Bus Shield</a>, and tried the SparkFun_CAN_Demo from <a href="https://learn.sparkfun.com/tutorials/can-bus-shield-hookup-guide" rel="nofollow noreferrer" title="Sparkfun Can Shield Tutorial">here</a> but the program only prints "CAN-Bus Demo" and then does nothing, even when I have it connected into my vehicle's OBD-II port and the key is turned to ON (I can't run the engine because I am in my garage). Any help will be appreciated.</p>
 23841: <p>SPI pins are located on different pins in Arduino Mega. You have to wire it correctly with your shield. Some shields uses ICSP (6-pin header) for better compatibility but this one doesn't.</p>

<p>See <a href="https://www.arduino.cc/en/Reference/SPI" rel="nofollow">Arduino SPI Reference</a> for more details (section: Connections)</p>
