Nissan Qashqai J11. Manual - part 1861

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COMPONENT PARTS

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< SYSTEM DESCRIPTION >

[CAN]

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1.

Electric park brake control unit

2.

Air bag diagnosis sensor unit

3.

Not applicable

4.

Steering angle sensor

5.

Combination meter

6.

Data link connector

7.

EPS control unit

8.

Distance sensor

9.

Sonar control unit

10. NAVI control unit

11.

ABS actuator and electric unit (con-
trol unit)

12. TCM (HRA2DDT and R9M engine 

models)

13. ECM

14. TCM (MR20DD engine models)

15. IPDM E/R

16. Around view monitor control unit

17. BCM

18. Chassis control module

19. • A/C auto amp. (With auto A/C)

• A/C amp. (Without auto A/C)

20. Front camera unit

21. 4WD control unit

JSMIA1783ZZ

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< SYSTEM DESCRIPTION >

[CAN]

SYSTEM

SYSTEM

CAN COMMUNICATION SYSTEM

CAN COMMUNICATION SYSTEM : System Description

INFOID:0000000010330307

SYSTEM DIAGRAM

DESCRIPTION

• CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle

multiplex communication line with high data communication speed and excellent error detection ability. Many
electronic control units are equipped onto a vehicle, and each control unit shares information and links with
other control units during operation (not independent). In CAN communication, control units are connected
with 2 communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with
less wiring. Each control unit transmits/receives data but selectively reads required data only.

• The following control units include a gateway function and communicate signals between the different CAN

communication circuits.

CAN Communication Signal Generation

JSMIA1716GB

CAN communication circuit 

Gateway control unit

Reference

CAN communication circuit 1 

⇔

 CAN communication circuit 2

BCM

BCS-9, "BODY CONTROL SYSTEM : 
System Description"

CAN communication circuit 1 

⇔

 Chassis communication cir-

cuit

Chassis control module

DAS-226, "System Description - Chas-
sis Control"

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SYSTEM

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< SYSTEM DESCRIPTION >

[CAN]

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• Termination circuits (resistors) are connected across the CAN communication system. When transmitting a

CAN communication signal, each control unit passes a current to the CAN-H line and the current returns to
the CAN-L line.

• The current flows separately into the termination circuits connected

across the CAN communication system and the termination cir-
cuits drop voltage to generate a potential difference between the
CAN-H line and the CAN-L line.
NOTE:
A signal with no current passage is called “Recessive” and one
with current passage is called “Dominant”.

• The system produces digital signals for signal communications, by

using the potential difference.

The Construction of CAN Communication Signal (Message)

JSMIA0450GB

JSMIA0543GB

JSMIA0544ZZ

JSMIA0545ZZ

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< SYSTEM DESCRIPTION >

[CAN]

SYSTEM

CAN Communication Line

The CAN communication line is a twisted pair wire consisting of
strands of CAN-H 

 and CAN-L 

 and has noise immunity.

NOTE:
The CAN communication system has the characteristics of noise-resistant because this system produces dig-
ital signals by using the potential difference between the CAN-H line and the CAN-L line and has the twisted
pair wire structure.
Since the CAN-H line and the CAN-L line are always adjacent to
each other, the same degree of noise occurs, respectively, when a
noise 

 occurs. Although the noise changes the voltage, the poten-

tial difference 

 between the CAN-H line and the CAN-L line is

insensitive to noise. Therefore, noise-resistant signals can be
obtained.

CAN Signal Communications

Each control unit of the CAN communication system transmits signals through the CAN communication con-
trol circuit included in the control unit and receives only necessary signals from each control unit to perform
various kinds of control.

No.

Message name

Description

1

Start of frame (1 bit)

Start of message.

2

Arbitration of field (11 bit)

Priorities of message-sending are shown when there is a pos-
sibility that multiple messages are sent at the same time.

3

Control field (6 bit)

Signal quantity in data field is shown.

4

Data field (0-64 bit)

Actual signal is shown.

5

CRC field (16 bit)

• The transmitting control unit calculates sending data in ad-

vance and writes the calculated value in a message.

• The receiving control unit calculates received data and judg-

es that the data reception is normal when the calculated val-
ue is the same as the value written in the sent data. 

6

ACK field (2 bit)

The completion of normal reception is sent to the transmitting 
unit.

7

End of frame (7 bit)

End of message.

JSMIA0382ZZ

JSMIA0383ZZ