Mazda 6. Manual — part 347

T–144

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]

DTC U0073, U1900, U2516

A6E816255430W05

Diagnostic procedure

DTC

U0073

CAN system communication error

U1900

U2516

CAN system wiring harness open and short circuit

DETECTION

CONDITION

Warning
• Detection conditions are for understanding DTC outline before performing inspection.

Performing inspection with only detection conditions may cause injury due to operating error
or damage the system. When performing inspection, always follow inspection procedure.

• CAN system related harness malfunction

• Related module communication error

POSSIBLE

CAUSE

• Open or short circuit in wiring harness

• Malfunction of connectors between PCM, ABS (ABS/TCS) HU/CM or DSC HU/CM and Instrument

cluster

• PCM malfunction

• ABS (ABS/TCS) HU/CM malfunction (with ABS (ABS/TCS))

• DSC HU/CM malfunction (with DSC)

• Instrument cluster malfunction

STEP

INSPECTION

ACTION

DETERMINING THE LOCATION OF A
MALFUNCTION

• Determine the malfunctioning part of the

CAN system.
(See

T–142 PROCEDURES FOR

DETERMINING THE LOCATION OF A
MALFUNCTION

)

• Is the malfunctioning part the wiring harness

C or the instrument cluster?

Yes

Go to Step 4.

Go to next step.

DETERMINING THE LOCATION OF A
MALFUNCTION

• Is the malfunctioning part the wiring harness

B or the ABS (ABS/TCS) HU/CM? (with ABS
(ABS/TCS))

• Is the malfunctioning part the wiring harness

B or the DSC HU/CM? (with DSC)

Yes

Go to Step 8.

Go to next step.

DETERMINING THE LOCATION OF A
MALFUNCTION

• Is the malfunctioning part the wiring harness

A or the PCM?

Yes

Go to Step 12.

Troubleshooting completed.

INSPECT INSTRUMENT CLUSTER
CONNECTOR

• Disconnect negative battery cable.

• Disconnect instrument cluster connector.

• Is poor connection detection bars of

instrument cluster connector okay?

Yes

Go to next step.

Replace wiring harness.

• Is vehicle equipped with DSC?

Yes

Go to next step.

Go to Step 7.

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]

T–145

INSPECT WIRING HARNESS BETWEEN DSC
HU/CM AND INSTRUMENT CLUSTER

• Disconnect DSC HU/CM connector.

• Inspect following wiring harness between

DSC HU/CM and instrument cluster
terminals for short to ground, short power
supply, and open circuit:
— AF—2W (CAN_L)
— AG—2X (CAN_H)

• Is wiring harness okay?

Yes

Replace instrument cluster, then go to Step 16.

Replace wiring harness.

INSPECT WIRING HARNESS BETWEEN ABS
(ABS/TCS) HU/CM AND INSTRUMENT
CLUSTER

• Disconnect ABS (ABS/TCS) HU/CM

connector.

• Inspect following wiring harness between

ABS (ABS/TCS) HU/CM and instrument
cluster terminals for short to ground, short
power supply, and open circuit:
— R—2W (CAN_L)
— O—2X (CAN_H)

• Is wiring harness okay?

Yes

Replace instrument cluster, then go to Step 16.

Replace wiring harness.

INSPECT ABS (ABS/TCS) HU/CM OR DSC
HU/CM CONNECTOR

• Disconnect negative battery cable.

• Disconnect ABS (ABS/TCS) HU/CM or DSC

HU/CM connector.

• Is poor connection detection bars of ABS

(ABS/TCS) HU/CM or DSC HU/CM
connector okay?

Yes

Go to next step.

Replace wiring harness.

• Is vehicle equipped with DSC?

Yes

Go to next step.

Go to Step 11.

INSPECT WIRING HARNESS BETWEEN DSC
HU/CM AND INSTRUMENT CLUSTER

• Disconnect instrument cluster connector.

• Inspect following wiring harness between

DSC HU/CM and instrument cluster
terminals for short to ground, short power
supply, and open circuit:
— AF—2W (CAN_L)
— AG—2X (CAN_H)

• Is wiring harness okay?

Yes

Replace DSC HU/CM , then go to Step 16.

Replace wiring harness.

INSPECT WIRING HARNESS BETWEEN ABS
(ABS/TCS) HU/CM AND INSTRUMENT
CLUSTER

• Disconnect instrument cluster connector.

• Inspect following wiring harness between

ABS (ABS/TCS) HU/CM and instrument
cluster terminals for short to ground, short
power supply, and open circuit:
— R—2W (CAN_L)
— O—2X (CAN_H)

• Is wiring harness okay?

Yes

Replace ABS (ABS/TCS) HU/CM , then go to Step 16.

Replace wiring harness.

INSPECT PCM CONNECTOR

• Disconnect negative battery cable.

• Disconnect PCM connector.

• Is poor connection detection bars of PCM

connector okay?

Yes

Go to next step.

Replace wiring harness.

• Is vehicle equipped with DSC?

Yes

Go to next step.

Go to Step 15.

STEP

INSPECTION

ACTION

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM],

ON-BOARD DIAGNOSTIC [DISCHARGE HEADLIGHT]

T–146

End Of Sie

FOREWORD

A6E818867000W01

Outline

• The OBD (on-board diagnostic) test inspects the integrity and function of the discharge headlight and output

the results when requested by the specific tests.

• OBD test also:

— Provides a quick inspection of the discharge headlight.
— Is usually performed at the start of each diagnostic procedure.
— Provides verification after repairs to ensure that no other faults occurred during service.

• Diagnostic DTC can be read/cleared, using the SST (WDS or equivalent)

Read/clear diagnostic results

• This function allows you to read or clear DTCs in the discharge headlight control unit (LH) memory.

Reading DTCs Procedure Using WDS or equivalent

1. Connect SST (WDS or equivalent) to the vehicle

DLC-2 16-pin connector.

2. Turn the ignition switch to ON (Engine OFF) or

start engine.

3. Retrieve DTC by SST (WDS or equivalent).

End Of Sie

INSPECT WIRING HARNESS BETWEEN PCM
AND DSC HU/CM

• Disconnect negative battery cable.

• Disconnect DSC HU/CM connector.

• Inspect following wiring harness between

PCM and DSC HU/CM terminals for short to
ground, short power supply, and open circuit:
— 2R—AF (CAN_L)
— 2U—AG (CAN_H)

• Is wiring harness okay?

Yes

Replace PCM, then go to Step 16.

Replace wiring harness.

INSPECT WIRING HARNESS BETWEEN PCM
AND ABS (ABS/TCS) HU/CM

• Disconnect negative battery cable.

• Disconnect ABS (ABS/TCS) HU/CM

connector.

• Inspect following wiring harness between

PCM and ABS (ABS/TCS) HU/CM terminals
for short to ground, short power supply, and
open circuit:
— 2R—R (CAN_L)
— 2U—O (CAN_H)

• Is wiring harness okay?

Yes

Replace PCM, then go to next step.

Replace wiring harness.

CHECK DTC INDICATE

• Connect PCM connector.

• Connect ABS (ABS/TCS) HU/CM or DSC

HU/CM connector.

• Connect instrument cluster connector.

• Clear DTC from module memory using SST

(WDS or equivalent).

• Perform KOEO/KOER self-test.

• Are DTCs U0073, U1900 and/or U2516

indicated?

Yes

Repeat from Step 1.

Troubleshooting completed.

STEP

INSPECTION

ACTION

ON-BOARD DIAGNOSTIC [DISCHARGE HEADLIGHT]

DLC-2

A6E3970W002

ON-BOARD DIAGNOSTIC [DISCHARGE HEADLIGHT]

T–146–1

T–146BODY ELECTRICAL SYSTEM

Clearing DTCs Procedures Using WDS or equivalent

1. After repairs have been made, perform the reading DTCs procedure.
2. Turn the ignition switch to ON (Engine OFF) or start engine.
3. Erase DTC by SST (WDS or equivalent).
4. Ensure that the customer

′s concern has been resolved.

PID/Data Monitor and Record Procedure

1. Connect WDS or equivalent to the vehicle DLC-2

16-pin connector.

2. Turn the ignition switch to ON (Engine OFF) or

start engine.

3. Access and monitor PIDs by SST (WDS or

equivalent).

Note

• The data monitor function monitors the

calculated values of input/output signals in
the discharge headlight control unit (LH) and
the discharge headlight control unit (RH),
and it does not directly display monitored
value faults as faults in input/output parts
themselves. If a monitored value is not within the specification it will be necessary to inspect input/output
parts separately by such means as DTC inspection or the active command modes function.

End Of Sie

DTC TABLE

A6E818867000W02

• DTCs are common for present and past malfunction diagnosis.

End Of Sie

PID/DATA MONITOR TABLE

A6E818867000W03

LHID

ON-BOARD DIAGNOSTIC [DISCHARGE HEADLIGHT]

DLC-2

A6E3970W002

DTC Description