ON-BOARD DIAGNOSTIC FUNCTION [CAN (CONTROLLER AREA NETWORK)]

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Block Diagram

HS-CAN

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MS-CAN

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On-Board Diagnostic Function


Malfunction detection function

•  The failure detection function in each CAN system-related module detects malfunctions in input/output signals.
•  This function outputs the DTC for the detected malfunction to the DLC-2, and also sends the detected result to the memory function and fail-safe function.


Fail-safe function

•  When the failure detection function determines that there is a malfunction, the fail-safe function illuminates a warning light to inform the driver of the malfunction.


Memory function

•  The memory function stores the DTC for the malfunction of input/output signals for related parts, as determined by the failure detection function.


Self-malfunction diagnostic function

•  The self-malfunction diagnostic function determines that there is a malfunction, and outputs a signal, as a DTC, to the DLC-2. The DTC can be read out using the Mazda Modular Diagnostic System (M-MDS).

HS-CAN

DTC Output Unit

DTC

Malfunction location
Instrument cluster
U1900
CAN system communication error
U2023
Abnormal message from PCM
U2064
Warning light illumination request signal from other modules
U2516
CAN system wiring harness open or short circuit
PCM
U0073
Module communication error (CAN bus)
U0101
Communication error to TCM
U0121
DSC HU/CM communication error
U0155
Communication error to instrument cluster
U0167
Communication error to keyless control module
DSC HU/CM
U0073
Module communication error (CAN bus)
U0100
PCM communication error
U0101
Communication error to TCM
U0155
Communication error to instrument cluster
U1900
CAN system communication error
U2023
Abnormal message from PCM
EPS control module
U0073
Module communication error (CAN bus)
U1900
CAN system communication error
U2023
Abnormal message from PCM
TCM
U0073
CAN system communication error
U0100
PCM communication error
U0121
DSC HU/CM communication error
Keyless control module
U0073
Module communication error (CAN bus)
U0100
PCM communication error
U1147
Communication error to PCM
U2023
Abnormal message from PCM
U2510
Communication error to PCM
Steering angle sensor
U1900
CAN system communication error
U2516
CAN system wiring harness open or short circuit

MS-CAN

DTC Output Unit

DTC

Malfunction location
Information display
U0164
Communication error to climate control unit
U0184
Communication error to audio unit
U2516
CAN system communication error
Audio unit
16:Er12
CAN system communication error
Car-navigation unit
Device code 16/error code 12
CAN system communication error
Device code 17/error code 11
Communication error to instrument cluster
Hands-free telephone unit (with audio unit)
26:Er81
CAN system communication error
Hands-free telephone unit (with car-navigation unit)
Device code 26/error code 81
CAN system communication error


PID/data monitoring function

•  The PID/data monitoring function is used to freely select and read out, in real time, the monitored items for the input/output signals of the DSC HU/CM and instrument cluster.
•  An SST (M-MDS or equivalent) is used to read out the PID/data monitor information.

PID/data monitor table

PID name (definition)

Condition

Specification

PID monitor module

Terminal
ABS_MSG
(Missing message from the DSC HU/CM)
Present
Circuit in the DSC HU/CM is normal.
Instrument cluster
•  DSC HU/CM: X, W
•  Instrument cluster: 1J, 1L
Not Present
Circuit in the DSC HU/CM is disable.
EPS_MSG
(Missing message from the EPS control module)
Present
Circuit in the EPS control module is normal
•  EPS control module: M, K
•  Instrument cluster: 1J, 1L
Not Present
Circuit in the EPS control module is disable
PCM_MSG
(Missing message from the PCM)
Present
Circuit in the PCM is normal.
•  PCM: 1AM, 1AI
•  Instrument cluster: 1J, 1L
Not Present
Circuit in the PCM is disable.
TCM_MSG
(Missing message from the TCM)
Present
Circuit in the TCM is normal.
•  TCM: 1G, 1C
•  Instrument cluster: 1J, 1L
Not Present
Circuit in the TCM is disable.


Narrowing down malfunction locations

•  When the CAN system is thought to be malfunctioning based on the repair order form and the malfunctioning symptom, perform the CAN system on-board diagnosis.
•  DTCs are output due to a control module or sensor malfunction, or incorrect power supply. Verify the output DTCs and first inspect the DTCs not shown in the DTC table.
•  The open circuit location in the CAN system can be determined by verifying the DTCs detected in each module and by the module which has failed.
•  It is possible for signal error DTCs to be output in addition to communication error DTCs if there is an open circuit. Determine the open circuit location if the communication error and signal error DTCs are output simultaneously.
•  For DTC details, refer to the “Self-malfunction diagnostic function”. (See Self-malfunction diagnostic function.)

Troubleshooting procedure

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Example (L.H.D.): DSC HU/CM-related wiring harness open circuit (if DTC is output)

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

Module

Displayed DTC

Probable malfunction location
PCM
U0121
DSC HU/CM communication error
TCM
U0121
DSC HU/CM communication error

Module

Fail
DSC HU/CM
×

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2.  The wiring harness between the DSC HU/CM and branch B, or the DSC HU/CM itself could have a malfunction because the DTCs indicating a communication error between the DSC HU/CM and PCM/TCM, in addition to "Fail" on the DSC HU/CM, are displayed even though communication between the PCM and TCM is normal.


Example (R.H.D.): DSC HU/CM-related wiring harness open circuit (if DTC is output)

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

Module

Displayed DTC

Probable malfunction location
PCM
U0121
DSC HU/CM communication error
TCM
U0121
DSC HU/CM communication error

Module

Fail
DSC HU/CM
×

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2.  The wiring harness between the DSC HU/CM and branch B, or the DSC HU/CM itself could have a malfunction because the DTCs indicating a communication error between the DSC HU/CM and PCM/TCM, in addition to "Fail" on the DSC HU/CM, are displayed even though communication between the PCM and TCM is normal.