Monitoring the Nissan Leaf using an ELM327 diagnostic tool

An introduction to reading the Car-CAN bus of the Nissan Leaf using an ELM327 compatible diagnostic tool.

Requirements

  1. ELM327 compatible OBD-II diagnostic tool.

  2. Terminal application running on a mobile or laptop.

  3. Nissan Leaf.

The examples in this tutorial use a Vgate Wi-Fi diagnostic tool and Serial Wi-Fi Terminal for Android by Kai Morich. The same developer has also written Serial USB Terminal and Serial Bluetooth Terminal for Android.

The vehicle used in this tutorial is:

Vehicle

Nissan Leaf

Year

2013

Model

AZE0-0 G-spec

CAN protocol

ISO 15765‑4 (CAN 11/500)

ELM327 OBD-II diagnostic tool

ELM327 diagnostic tools are available supporting either wireless or wired communication protocols. Wireless communication protocols include:

  • BT

  • BTL

  • Wi-Fi

Wi-Fi diagnostic tools have the disadvantage that while in use your mobile or laptop is unable to connect to any other Wi-Fi network.

The most common wired communication protocol is USB.

Note

Unfortunately the market is flooded with counterfeit ELM327 microcontrollers which have made their way into inexpensive diagnostic tools. Often these devices do not fully support the ELM327 specification [JRPollock17].

Genuine ELM327 microcontrollers are supplied by ELM Electronics Inc. who recommend seeking the assurance from the device vendor that they use genuine ELM parts [elm20].

Terminal application

Select a terminal application that can be configured to connect to your diagnostic tool via the appropriate communication protocol.

Nissan Leaf

The Leaf has three CAN buses commonly referred to as: Car-CAN, EV-CAN, and AV-CAN. The diagnostic connector CAN pin assignments are depicted in Figure 3 and listed in Table 8. The CAN protocol used in the Car-CAN bus of the Leaf is ISO 15765-4 CAN (11-bit ID, 500 kBd) which is often abbreviated to “ISO 15765‑4 (CAN 11/500).”

Nissan Leaf OBD-II diagnostic connector pin assignment

Figure 3 Nissan Leaf ISO 15031-3 diagnostic connector pin assignment (mating-end view)

Table 8 Nissan Leaf ISO 15031-3 diagnostic connector CAN bus pin assignments

CAN bus

Diagnostic connector pins

CAN high

CAN low

Car-CAN

Car-CAN high 6

Car-CAN low 14

EV-CAN

EV-CAN high 12

EV-CAN low 13

AV-CAN

AV-CAN high 3

AV-CAN low 11

Standard OBD-II diagnostic tools connect to the Car-CAN bus on pins 6 and 14.

The Leaf does not support any the standard PIDs which are mandated for internal combustion engine vehicles. This is despite having a OBD-II diagnostic connector in compliance with ISO 15031-3, and the CAN protocols complying with ISO 15765‑4.

In addition to the Leaf not supporting standard PIDs there can be PID variations between Leaf models.

Set up

Set up involves connecting the diagnostic tool to the vehicle and configuring the terminal application which runs on your mobile or laptop.

Warning

Using a poor quality diagnostic tool may cause the vehicle to behave unexpectedly.

Connect the diagnostic tool

Insert the diagnostic tool into the vehicle’s OBD-II diagnostic connector – which is found beneath the steering column. Then power-on the vehicle to activate the Car-CAN bus.

Configure the terminal application

Configuration of the terminal application depends on the communication protocol supported by your diagnostic tool and the terminal software being used.

Wi-Fi:

  1. Connect to the diagnostic tool as you would connect to a Wi-Fi access point.

  2. Configure the terminal application with the host and port of the diagnostic tool according to the user guide. Common configuration is:

    Host

    192.168.0.10

    Port

    35000

    Protocol

    Raw

Bluetooth and Bluetooth Low Energy:

  1. Pair the diagnostic tool with your mobile or laptop.

  2. Once paired the tool is available for selection in the terminal application.

Diagnostic tool commands

The ELM327 is instructed by sending a series of AT commands from the terminal application.

AT commands

Commands used in this tutorial are listed in table Table 9. The complete ELM327 command set can be found in the ELM327 specification.

Table 9 ELM327 AT commands used in this tutorial [elm16]

Command

Description

ATZ

reset all

ATI

print the ELM327 firmware version ID

ATL1

line feed on

ATH1

header control on

ATS1

print spaces on

ATAL

allow long messages

ATSP6

set CAN protocol to ISO 15765-4 CAN (11/500)

ATCRA 358

filter message with PID 0x358

ATMA

monitor all

Read turn signal status

In Listing 5 the status of the vehicle’s turn signal is read. Commands on lines 1 to 7 initialise the ELM327. Command ATCRA 358 on line 8 filters messages with the PID 0x358.

Listing 5 Read PID 0x358 – turn signal status
 1> ATZ
 2> ATI
 3> ATL1
 4> ATH1
 5> ATS1
 6> ATAL
 7> ATSP6
 8> ATCRA 358
 9> ATMA
10358 00 08 80 00 00 00 00 00
11358 00 08 80 00 00 00 00 00
12358 00 08 80 00 00 00 00 00
13358 00 08 82 00 00 00 00 00
14358 00 08 82 00 00 00 00 00
15358 00 08 82 00 00 00 00 00
16358 00 08 80 00 00 00 00 00
17358 00 08 80 00 00 00 00 00
18358 00 08 80 00 00 00 00 00
19358 00 08 84 00 00 00 00 00
20358 00 08 84 00 00 00 00 00
21358 00 08 84 00 00 00 00 00

ELM327 session 0x358 turn signal status

The output is displayed following the command ATMA on lines 10 to 21. As the turn signal leaver is operated the third byte changes correspondingly:

off

8016 = 100000002

left signal

8216 = 100000102

right signal

8416 = 100001002

A screenshot of the serial terminal session prior to executing ATMA is shown in Figure 4.

ELM327 serial terminal session on an Android-powered device

Figure 4 ELM327 serial terminal session on an Android-powered device [KaiMorich]

See also

Diagnostic connector

Detailed description of the Leaf OBD-II diagnostic connector.

358 turn signal

PID 0x358 Turn signal.