The CANbus network in the LEAF is the central nervous system, connecting all the major modules and relaying information between them. This thread is a place for like-minded hackers to share information on the LEAF's CANbus topology, message contents, experiments, and gleaned information from the car data systems.
The LEAF Service Manual (LAN section in particular) has thorough information regarding the connectivity, pinouts, and functional blocks on the CANbus. However, it does not describe the actual message packets. Specific diagnostics and operations are documented only for the CONSULT III+. By studying the CANbus directly, it is possible we can extract more information than the car displays to the user, and possibly perform some operations done by the CONSULT tool.Data Link Connector
There are three CAN (Controller Area Network) network pairs brought out to the 16-pin DLC (Data Link Connector), labeled (M4) in the service manuals. This connector is located above the driver's left knee, and is sometimes referred to as an OBD or SAE J1962 connector. Be very careful about buying OBD "code scanner" products, as they generally use an unrelated OBD data bus (ISO 9141-2 "K-Line" or "L-Line") for low-speed communication, and are useless for monitoring the CAN bus.
This image shows the pinout of the female (car
) connector:Primary CAN Bus, "CAN communication circuit"
The primary CAN bus is on the standardized (J2284) connector pins, CAN-L (14) and CAN-H (6). Most off-the-shelf CAN car adapters will use this wire pair exclusively.
This bus carries traffic between the VCM, DLC, BCM, ABS, Steering, and Dash/Nav. It has most of the interior operations, displays, and controls.EV CAN, "EV system CAN circuit"
The second bus is the "EV CAN". This is on Discretionary pins in the DLC: EV CAN-L (12), EV CAN-H (13).
This bus has communication including the VCM, HVBAT, OBC, and TCU.
Note that VCM is on both the CAN & EV-CAN busses and can gateway traffic between them. The chart on page LAN-33 has a detailed list of each signal, and which bus/module transmits/receives it.
Because the OBC, Motor, and HVBAT are on the EV CAN bus only, this has been the primary area of my interest. To connect to this bus, you will likely have to make your own J1962 cable, as it is not the 'default' CAN bus for diagnostic tools.AV CAN
There is a third less-documented CAN bus between the Audio-Video Navigation unit and the "multifunction switch". (The multifunction switch is the physical button panel around the A/V screen.. Map, Eco, Menu, etc.)
AV-CAN-L (3)CHAdeMO Quick Charge
The CHAdeMO DC quick charge port (on cars so equipped) has an additional CAN connection to the On Board Charger. Anyone know more about the pinout here?Power
Pin 16 has constant +12v DC power from the battery. It is protected by a 10A fuse #13.
Pin 8 has switched power when the Leaf is ON, protected by 10A fuse #3. This is a nonstandard pin assignment, and most commercial devices use the constant power found on Pin 16.
120 Watts is enough power to melt small-gauge wire, so an additional fuse is recommended for any DIY project.
Pin 4 is Chassis Ground, and Pin 5 is Signal Ground. Note that CAN is a differential bus, and has no need for a Ground reference. Indeed, if you can power externally, isolation is preferred. It appears that 4 & 5 are both wired to battery ground in the Leaf.USB
The TCU and Navigation unit are connected via USB 1.0. This is the link used to update Carwings information feeds, Charger location updates, etc. This data may not be on CANbus at all. (The TCU also has logic-level RS-232 available on its connector harness, apparently unused by the Leaf.)