Mazda X-5. Manual — part 123

CONTROL SYSTEM

09–40–5

09–40

On-Board Diagnostic Function

• The on-board diagnostic function is incorporated into the following module:

— PCM

— TCM

— DSC HU/CM (with DSC)

— ABS HU/CM (with ABS)

— Keyless control module

— Steering angle sensor

— Instrument cluster

• This function can narrow down CAN system malfunction locations.

• The on-board diagnostic function consists of the following functions.

— Failure detection function, which detects DTCs malfunctions in CAN system-related parts.

— Memory function, which stores detected.

— Self-malfunction diagnostic function, which indicates system malfunctions using DTCs and warning lights.

• Using the WDS or equivalent, DTCs can be read out and deleted.

• The CAN system has a fail-safe function. When a malfunction occurs in CAN system, the transmission module

sends a warning signal and the receiving module illuminates the warning light.

Block diagram

Failure 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 WDS or equivalent.

F

E

Z

Y

1J

1L

:

:

CAN_H

CAN_L

DLC-2

1AI

1AM

4AA

4Z

1G

1C

PCM

ABS HU/CM
(WITH ABS)

KEYLESS
CONTROL MODULE
(WITH ADVANCED
KEYLESS SYSTEM)

TCM (AT)

INSTRUMENT
CLUSTER

TWISTED PAIR

X

W

DSC HU/CM
(WITH DSC)

E

F

STEERING
ANGLE
SENSOR
(WITH DSC)

E5U940ZS5002

CONTROL SYSTEM

09–40–6

DTC table

Narrowing down malfunction locations

• The on-board diagnostic function, by verifying the detected DTC information from each module, can narrow

down a CAN system malfunction location. Refer to the self-malfunction diagnostic function for detailed
information regarding DTCs. (See09–40–5 Self-malfunction diagnostic function.)

Flowchart

DTC

Malfunction location

DTC output module

U0073

CAN system communication error

• PCM

• TCM

• ABS HU/CM

• DSC HU/CM

• Keyless control module

• Instrument cluster

U0100

Communication error to PCM

• TCM

• DSC HU/CM

• Keyless control module

• Instrument cluster

U0101

Communication error to TCM

• PCM

• DSC HU/CM

• Instrument cluster

U0121

Communication error to ABS HU/CM or DSC HU/CM

• PCM

• Instrument cluster

U0155

Communication error to instrument cluster

• PCM

• DSC HU/CM

U0214

Communication error to keyless control module

Instrument cluster

U0323

Communication error to instrument cluster

Keyless control module

U1900

Communication error to other module

• ABS HU/CM

• DSC HU/CM

• Steering angle sensor

U2023

Abnormal message from PCM

• ABS HU/CM

• DSC HU/CM

• Keyless control module

U2516

CAN system communication error

Steering angle sensor

START

Verify that DTCs are displayed for PCM, TCM, DSC HU/CM, ABS HU/CM, keyless control module,
steering angle sensor, and instrument cluster.
Are any DTCs display?

Yes

No

END

Determine the malfunctioning part of the CAN system.

END

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CONTROL SYSTEM

09–40–7

09–40

Example (PCM-related communication error)

Note

• This example is for MT with DSC.

1. DTCs for the PCM, DSC HU/CM, steering angle sensor and instrument cluster can be verified using the WDS

or equivalent.

2. If there is a communication error between the instrument cluster and PCM, even if the communication between

the DSC HU/CM and the instrument cluster is normal, it is probable that there is a malfunction in the PCM or
PCM-related wiring harnesses.

End Of Sie

Module

Displayed DTC

Probable malfunction location

PCM

U0073

PCM-related CAN system malfunction

U0121

Communication error between PCM and DSC HU/CM

U0155

Communication error between PCM and instrument cluster

DSC HU/CM

U0100

Communication error between DSC HU/CM and PCM

Instrument cluster

U0100

Communication error between instrument cluster and PCM

DLC-2

PCM

: TWISTED PAIR

INSTRUMENT CLUSTER

DSC HU/CM

NORMAL

COMMUNICATION
ERROR

COMMUNICATION
ERROR

E5U940ZS5004