MULTIPLEX COMMUNICATION SYSTEM

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Outline

•  A control area network (CAN) system has been adopted in which the multiple control modules send/receive signals using two common communication lines.
•  Local CAN, ISO communication, or LIN communication has been adopted for the individual communication between control modules in consideration of the communication speed and the cost.

System Wiring Diagram

Note
•  The following figure shows the CAN/LIN communication/ISO communication/local CAN connection conditions. The availability of the equipment may differ depending on the vehicle specifications.

L.H.D.

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R.H.D.

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Structural View

Note
•  The following figure shows the installation positions for the equipment which perform CAN communication. The availability of the equipment may differ depending on the vehicle specifications.

L.H.D.

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R.H.D.

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Function


CAN (controller area network) system

•  HS-CAN (high-speed controller area network) is used for communication between the following modules:
―  PCM
―  DSC HU/CM
―  Radar unit (With smart brake support (SBS))
―  Front body control module (FBCM)
―  TCM
―  Adaptive LED headlights control module (With adaptive LED headlights)/auto leveling control module (Without adaptive LED headlights)
―  DC-DC converter (i-ELOOP) (With i-stop system)
―  Position memory control module (With driver-side memory power seat)
―  Power liftgate (PLG) control module (With power liftgate (PLG) system)
―  Audio amplifier (With Bose® type audio)
―  4WD control module (4WD)
―  Electric parking brake control module
―  Rear one-touch walk-in control module
―  Laser sensor (With laser sensor)
―  Forward sensing camera (FSC) (With forward sensing camera (FSC))
―  EPS control module
―  SAS control module
―  Start stop unit
―  Connectivity master unit (CMU)
―  Active driving display (With active driving display)
―  Tuner and amp unit (TAU) (Without Bose® type audio)
―  MAZDA ERA-GLONASS control module (With MAZDA ERA-GLONASS)
―  Instrument cluster
•  MS-CAN (mid-speed controller area network) is used for communication between the following modules:
―  Instrument cluster
―  Parking assist unit (With parking sensor system)
―  Front climate control unit
―  Rear mount camera (With rear mount camera/predicted vehicle path assist lines display type)
―  360° view monitor control module (With 360° view monitor system)
―  Rear body control module (RBCM)
―  Blind spot monitoring (BSM) control module (LH) (With blind spot monitoring (BSM) system)


Malfunction diagnosis procedure

•  If a vehicle with a malfunction in a system controlled by a CAN system related module is brought in, verify the repair order form and the malfunctioning symptom first, then perform CAN malfunction diagnosis to determine if the malfunction cause is in the CAN system or not.
•  For CAN malfunction diagnosis, the voltage at the CAN connection terminal on the DLC-2 is measured, and based on the measured value, the CAN circuit can be examined or the malfunction symptom can be determined.
•  If the malfunction symptom is not an open circuit, inspect the voltage or continuity at the CAN circuit and determine the malfunctioning location.
•  If the malfunction symptom is an open circuit, determine the area of the open circuit by using the displayed communication error DTC and the module in which communication has failed.


Ex.) Open circuit location determination procedure

1.  Verify the CAN system-related module DTCs and the failed module using the Mazda Modular Diagnostic System (M-MDS).

DTC output module

Mazda Modular Diagnostic System (M-MDS) display

Output DTC
PCM
PCM
U0121:00
Radar unit
SBS/MRCC
U0121:00
TCM
TCM
U0121:00
Front body control module (FBCM)
F_BCM
U0121:00
Adaptive LED headlights control module
AFS/ALM
U0121:00
4WD control module
4X4
U0121:00
Electric parking brake control module
EPB
U0121:00
Laser sensor
SCBS
U0121:00
Forward sensing camera (FSC)
FSC
U0121:00
EPS control module
EPS
U0121:00
Connectivity master unit (CMU)
CMU
U0121:00
Start stop unit
SSU
U0121:00
U0121:87
Instrument cluster
IC
U0121:00

Module

Fail display
DSC HU/CM
×

2.  As a result of DTC verification, only DTCs related to DSC HU/CM and communication errors are output and the DSC HU/CM is indicated as failed, therefore there could be a malfunction in the DSC HU/CM or in the wiring harness between connector C-42 and DSC HU/CM.

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Local CAN

•  Local CAN is used for communication between the following modules:
―  Between PCM and TCM
―  Between connectivity master unit (CMU) and tuner and amp unit (TAU)
―  Between blind spot monitoring (BSM) control module (LH) and blind spot monitoring (BSM) control module (RH)


LIN communication

•  LIN communication is used for communication between the following modules:
―  Between PCM and active air shutter
―  Between PCM and engine oil level sensor
―  Between front body control module (FBCM) and auto light sensor/humidity sensor/rain sensor
―  Between front body control module (FBCM) and current sensor
―  Between rear body control module (RBCM) and intruder sensor
―  Between rear body control module (RBCM) and theft-deterrent siren
―  Between front climate control unit and rear climate control unit
―  Between adaptive LED headlights control module and front combination light (LH)
―  Between adaptive LED headlights control module and front combination light (RH)
―  Between connectivity master unit (CMU) and commander switch


ISO communication

•  ISO communication is used for communication between the following modules:
―  Between rear body control module (RBCM) and start stop unit
―  Between rear body control module (RBCM) and power window main switch


Construction


CAN

•  The HS-CAN has terminator resistors built into the following units which form the CAN lines.
―  Between PCM terminals 2AK (CAN_H) and 2AL (CAN_L)
―  Between instrument cluster terminals 1B (CAN_H) and 1D (CAN_L)
•  The MS-CAN has terminal resistors built into the following units which form the CAN lines.
―  Between rear body control module (RBCM) terminals 3E (CAN_H) and 3G (CAN_L)
―  Between instrument cluster terminals 1C (CAN_H) and 1E (CAN_L)


Local CAN

•  The local CAN has terminator resistors built into the following units which form the CAN lines.
―  Between PCM terminals 1A (CAN_H) and 1B (CAN_L)
―  Between TCM terminals G (CAN_H) and H (CAN_L)
―  Between connectivity master unit (CMU) terminals 2I (CAN_H) and 2J (CAN_L)
―  Between tuner and amp unit (TAU) terminals 1AA (CAN_H) and 1AB (CAN_L)
―  Between blind spot monitoring (BSM) control module (LH) terminals A (CAN_H) and B (CAN_L)
―  Between blind spot monitoring (BSM) control module (RH) terminals A (CAN_H) and B (CAN_L)


LIN communication

•  The LIN communication has drivers built into the following units which form the LIN communication lines.
―  PCM
―  Active air shutter
―  Engine oil level sensor
―  Front body control module (FBCM)
―  Auto light sensor/humidity sensor/rain sensor
―  Current sensor
―  Rear body control module (RBCM)
―  Intruder sensor
―  Theft-deterrent siren
―  Front climate control unit
―  Rear climate control unit
―  Adaptive LED headlights control module
―  Front combination light (LH)
―  Front combination light (RH)
―  Connectivity master unit (CMU)
―  Commander switch


ISO communication

•  The ISO communication has drivers built into the following units which form the ISO communication lines.
―  Rear body control module (RBCM)
―  Start stop unit
―  Power window main switch