Pinout

The screw terminal of WiCAN USB, position by position, and the termination resistor behind the TR position of the earlier boards.

The board, as drawn in the firmware's README, with the five-position terminal of the earlier boards. Current boards have four positions, without TR.

Position	Connect to
VIN	The supply, 7.5 V to 36 V: a 12 V car battery, a 24 V truck, a bench supply. Leave it open when the USB cable powers WiCAN.
GND	The ground of the bus and of the supply.
CANL	The CAN low wire of the bus.
CANH	The CAN high wire of the bus.
TR (earlier boards)	Nothing, or CANH to switch in the 120 Ω termination resistor: its other end is wired to CANL inside.

Boards with four positions have no termination inside: put a 120 Ω resistor across CANH and CANL when WiCAN sits at the end of a bus you build yourself. Hardware explains when a bus needs it, and covers power, the USB port and the LEDs.

Tapping a car's OBD port

Pin 6 is CAN high, pin 14 CAN low, pins 4 and 5 ground and pin 16 the battery, which can feed VIN. The WiCAN OBD pinout shows them.