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 (M-MDS display)

DTC

Malfunction location
PCM (PCM)
U0073
CAN system communication error
U0101
Communication error to TCM
U0121
Communication error to ABS HU/CM (With ABS)
Communication error to DSC HU/CM (With DSC)
U0155
Communication error to instrument cluster
TCM*1 (TCM)
U0073
CAN system communication error
U0100
Communication error to PCM
ABS HU/CM*2 (ABS)
U0073
CAN system communication error
U1900
Communication error to other module
U2023
Abnormal message from PCM
DSC HU/CM*3 (ABS)
U0073
CAN system communication error
U0100
Communication error to PCM
U0101
Communication error to TCM
U0155
Communication error to instrument cluster
U1900
Communication error to other module
U2023
Abnormal message from PCM
Power retractable hardtop control module (RHT)*4
U0073
CAN system communication error
U0100
Communication error to PCM
U0101
Communication error to TCM
U2197
Vehicle speed signal communication error
Active bonnet control module (DHS)*5
U0001:88
CAN system communication error
U0155:00
Communication error to instrument cluster
Instrument cluster (IC)
U0073
Module communication error
U0100
Communication error to PCM
U0101
Communication error to TCM
U0121
Communication error to ABS HU/CM (With ABS)
Communication error to DSC HU/CM (With DSC)
U0207
Communication error to power retractable hardtop control module
U0214
Communication error to keyless control module
U0250
Communication error to active bonnet control module
U2023
Abnormal message from PCM
U2197
Signal error from PCM

*1  :AT
*2  :with ABS
*3  :with DSC
*4  :with power retractable hardtop
*5  :with active bonnet

MS-CAN

DTC Output Unit

DTC

Malfunction location
Audio unit
16:Er12
Communication error between audio unit and HF/TEL unit
HF/TEL unit
26:Er81
CAN system communication error


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.) : TCM-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
U0101
Communication error to TCM
DSC HU/CM
U0101
Communication error to TCM
Power retractable hardtop control module
U0101
Communication error to TCM

Module

Fail
TCM
×

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2.  A communication error DTC is displayed for the signal between the TCM and PCM/DSC HU/CM/Power retractable hardtop control module despite normal communication between the PCM and instrument cluster. In addition, a TCM failure is displayed. This indicates that there may be a malfunction in the wiring harness between the TCM and branch A, or in the TCM itself.


Example (R.H.D.) : TCM-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
U0101
Communication error to TCM
DSC HU/CM
U0101
Communication error to TCM
Power retractable hardtop control module
U0101
Communication error to TCM

Module

Fail
TCM
×

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2.  A communication error DTC is displayed for the signal between the TCM and PCM/DSC HU/CM/Power retractable hardtop control module despite normal communication between the PCM and instrument cluster. In addition, a TCM failure is displayed. This indicates that there may be a malfunction in the wiring harness between the TCM and branch C, or in the TCM itself.