MAZDA 6 2002 Workshop Manual Suplement

T–40
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
Flowchart
•Use the following flowchart to verify the cause of the trouble.
End Of Sie
Repair the malfunctioning part by
following the DTC inspection.A
Inspect the power supply and the ground circuits for any units
that do not respond.
Are they normal?
Repair the malfunctioning part.A
A
B START
Using the SST (WDS or equivalent), verify if DTCs are displayed for PCM, TCM, ABS (ABS/TCS) HU/CM (with ABS (ABS/TCS)),
DSC HU/CM (with DSC), 4WD control module and instrument cluster.
Are any DTCs displayed?
Ye s
Are any DTCs other than the following displayed?
PCM: U0073, U0101, U0121, U0155
TCM: U0073, U0100
ABS (ABS/TCS) HU/CM, DSC HU/CM,
Instrument cluster: U1900, U2516
4WD control module: U0100, U0101, U0121
NoEND No
No Ye s
Are any of the following DTCs displayed?
PCM: U0073, U0101, U0121, U0155
TCM: U0073, U0100
ABS (ABS/TCS) HU/CM, DSC HU/CM,
Instrument cluster: U1900, U2516
4WD control module: U0100, U0101, U0121
Ye s
Ye s Narrow down CAN system malfunction location.
Using the SST (WDS or equivalent), verify if DTCs are displayed
for PCM, TCM, ABS (ABS/TCS) HU/CM, DSC HU/CM, 4WD
control module and instrument cluster.
Are any DTCs displayed?
No
Using the SST (WDS or equivalent), clear DTCs stored in
each module.
END
Ye s
No
Turn the ignition switch to the LOCK position.
Inspect the wiring harness and connector between
any unit that does not respond and the DLC-2.
PCM
—DLC-2 (except MZR-CD (RF Turbo))
2R—CAN_L
2U—CAN_H
PCM—DLC-2 (MZR-CD (RF Turbo))
39—CAN_L
13—CAN_H
TCM—DLC-2
2J—CAN_L
2M—CAN_H
ABS (ABS/TCS) HU/CM—DLC-2
X—KLN
DSC HU/CM—DLC-2
AB—KLN
4WD control module—DLC-2
H—CAN_L
G—CAN_H
Instrument cluster—DLC-2
2W—CAN_L
2X—CAN_H
Are the wiring harnesses and connectors normal? Is there a response from the PCM, TCM, ABS (ABS/TCS) HU/CM,
DSC HU/CM, 4WD control module and/or instrument cluster?
No Ye s
No
Ye s Repair the malfunctioning part by following the DTC inspection.
Repair the malfunctioning part.
A6E8162L101

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
T–40–1
T
T–40BODY ELECTRICAL SYSTEM
End Of Sie
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
Connect each unit connector.
Turn the ignition switch to the ON position.
Measure the voltage between DLC-2 terminals CAN_L and CAN_H.
Is the voltage 2.0—3.0 V?
Turn the ignition switch to the LOCK position.
Measure the resistance between DLC-2 terminals CAN_L and
CAN_H.
Is the resistance 59—65 ohms?
Replace any units that
do not respond.Disconnect the PCM connector.
Measure the resistance between PCM
connector terminals 2R and 2U
(except MZR-CD (RF Turbo)) or 13 and
39 (MZR-CD (RF Turbo)).
Is the resistance 118—130 ohms?
Replace the PCM.
Disconnect the instrument cluster connector.
Measure the resistance between instrument cluster connector
terminals 2W and 2X.
Is the resistance 118—130 ohms?
Replace the instrument
cluster.Turn the ignition switch to the LOCK position.
Disconnect the connector of any unit that does not respond.
(If there are two or more units that do not respond,
disconnect only one of the units.)
Turn the ignition switch to the ON position.
Measure the voltage between DLC-2 terminals CAN_L and
CAN_H.
Is the voltage 2.0—3.0 V?
The disconnected unit or the
related wiring harness may
have a malfunction.
Replace the disconnected unit. Replace the related wiring harness.The disconnected
unit is normal.
Are all units that do not respond disconnected?
Inspect if the related wiring harnesses (CAN_L
and/or CAN_H) have been shorted (to power
supply or ground).
If a short is found, replace the related wiring
harness. Ye sNo B
A A A AA
A
Turn the ignition switch to the LOCK position.
Verify the continuity between the following connector terminals of any disconnected unit.
PCM connector (except MZR-CD (RF Turbo)): 2R (CAN_L)—other terminals,
2U (CAN_H)—other terminals
PCM connector (MZR-CD (RF Turbo)): 39 (CAN_L)—other terminals,
13 (CAN_H)—other terminals
TCM connector: 2J (CAN_L)—other terminals, 2M (CAN_H)—other terminals
ABS (ABS/TCS) HU/CM connector: R (CAN_L)—other terminals,
O (CAN_H)—other terminals
DSC HU/CM connector: AF (CAN_L)—other terminals, AG (CAN_H)—other terminals
4WD control module connector: H (CAN_L)—other terminals, G (CAN_H)—other terminals
Instrument cluster connector: 2W (CAN_L)—other terminals, 2X (CAN_H)—other terminals
Is there continuity?
Ye s
No
Ye s
No
Ye sNo
Ye sNo
Ye sNo
Ye sNo
A6E8162L102

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
T–41
T
TBODY ELECTRICAL SYSTEMDTC TABLEA6E816255430202
End Of SiePID/DATA MONITOR TABLEA6E816255430203
End Of Sie
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
DTC Malfunction location Related module Page
U0073 CAN system communication error•PCM
•TCM(See T–45 DTC U0073,
U1900, U2516)
U0100 Communication error to PCM•TCM
•4WD control module
(See T–42 PROCEDURES
FOR DETERMINING THE
LOCATION OF A
MALFUNCTION) U0101 Communication error to TCM
•PCM
•4WD control module
U0121Communication error to ABS (ABS/TCS) HU/CM
or DSC HU/CM
U0155 Communication error to instrument cluster•PCM
U1900 CAN system communication error•ABS (ABS/TCS) HU/CM (with
ABS (ABS/TCS))
•DSC HU/CM (with DSC)
•Instrument cluster(See T–45 DTC U0073,
U1900, U2516)
U2516CAN system wiring harness open and short
circuit
PID name (definition) Condition Specification Related module Terminal
PCM_MSG
(Missing message from the
PCM)Present Circuit in the PCM is normal.•TCM
•ABS (ABS/TCS)
HU/CM or DSC
HU/CM
•Instrument
cluster
•TCM: 2J, 2M
•ABS (ABS/TCS)
HU/CM: O, R
•DSC HU/CM: AF,
AG
•Instrument cluster:
2W, 2X Not Present Circuit in the PCM is abnormal.
TCM_MSG
(Missing message from the
TCM)Present Circuit in the TCM is normal.•ABS (ABS/TCS)
HU/CM or DSC
HU/CM
•Instrument
cluster Not Present Circuit in the TCM is abnormal.
ABS_MSG
(Missing message from the
ABS (ABS/TCS) HU/CM or
DSC HU/CM)PresentCircuit in the ABS (ABS/TCS)
HU/CM or DSC HU/CM is
normal.•TCM
•Instrument
cluster
Not PresentCircuit in the ABS (ABS/TCS)
HU/CM or DSC HU/CM is
abnormal.
AWD_MSG
(Missing message from the
4WD control module)PresentCircuit in the 4WD control
module is normal.•TCM
•ABS (ABS/TCS)
HU/CM or DSC
HU/CM
•Instrument
cluster Not PresentCircuit in the 4WD control
module is abnormal.
IC_MSG
(Missing message from the
instrument cluster)PresentCircuit in the instrument cluster
is normal.•TCM
•ABS (ABS/TCS)
HU/CM or DSC
HU/CM Not PresentCircuit in the instrument cluster
is abnormal.

T–42
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
PROCEDURES FOR DETERMINING THE LOCATION OF A MALFUNCTIONA6E816255430204System Wiring Diagram
PCM
1. Check the display of DTC U0101, U0121 and/or U0155, using the SST (WDS or equivalent). (See T–41 DTC
TABLE.)
2. Referring to the following table, determine the malfunctioning part of the CAN system.
2WD
X: Normal
—: Communication error
PCMWIRING
HARNESS A
TWIST PAIRWIRING
HARNESS BWIRING
HARNESS C
INSTRUMENT
CLUSTER ABS (ABS/TCS)
HU/CM
OR
DSC HU/CM
TCM4WD
CONTROL
MODULE
WIRING
HARNESS EWIRING
HARNESS G
WIRING
HARNESS D
WIRING
HARNESS F
PCMWIRING
HARNESS A
INSTRUMENT
CLUSTER ABS (ABS/TCS)
HU/CM
OR
DSC HU/CM
WIRING
HARNESS C
WIRING
HARNESS B
2WD
4WD
A6E81621102
ModuleCommunication status
Malfunction location
ABS (ABS/TCS) HU/CM
DSC HU/CMInstrument cluster
PCM——•Wiring harness A
•PCM
—X•Wiring harness B
•ABS (ABS/TCS) HU/CM
•DSC HU/CM
X—•Wiring harness C
•Instrument cluster

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
T–43
T
4WD
X: Normal
—: Communication error
TCM
1. Access and monitor the “PCM_MSG”, “ABS_MSG”, “AWD_MSG” and “IC_MSG” of PID using the SST (WDS
or equivalent).
2. Referring to the PID/DATA MONITOR, confirm the display status of the PID. (See T–41 PID/DATA MONITOR
TABLE.)
3. Referring to the following table, determine the malfunctioning part of the CAN system.
X: Normal
—: Communication error
ABS (ABS/TCS) HU/CM or DSC HU/CM
1. Access and monitor the “PCM_MSG”, “TCM_MSG”, “AWD_MSG” and “IC_MSG” of PID using the SST (WDS
or equivalent).
2. Referring to the PID/DATA MONITOR, confirm the display status of the PID. (See T–41 PID/DATA MONITOR
TABLE.)
3. Referring to the following table, determine the malfunctioning part of the CAN system.
2WD
X: Normal
—: Communication error
ModuleCommunication status
Malfunction location
TCMABS (ABS/TCS) HU/CM
DSC HU/CMInstrument cluster
PCM———•Wiring harness A
•PCM
—XX•Wiring harness B
•TCM
X—X•Wiring harness D
•ABS (ABS/TCS) HU/CM
•DSC HU/CM
XX—•Wiring harness E
•Wiring harness G
•Instrument cluster
X——•Wiring harness C
ModuleCommunication status
Malfunction location
PCMABS (ABS/TCS)
HU/CM
DSC HU/CM4WD control
moduleInstrument cluster
TCM————•Wiring harness B
•TCM
—XXX•Wiring harness A
•PCM
X—XX•Wiring harness D
•ABS (ABS/TCS)
HU/CM
•DSC HU/CM
XX—X•Wiring harness F
•4WD control
module
XXX—•Wiring harness G
•Instrument cluster
X———•Wiring harness C
XX——•Wiring harness E
ModuleCommunication status
Malfunction location
PCM Instrument cluster
•ABS (ABS/TCS) HU/CM
•DSC HU/CM——•Wiring harness B
•ABS (ABS/TCS) HU/CM
•DSC HU/CM
—X•Wiring harness A
•PCM
X—•Wiring harness C
•Instrument cluster

T–44
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
4WD
X: Normal
—: Communication error
4WD control module
1. Check the display of DTC U0100, U0101 and/or U0121, using the SST (WDS or equivalent). (See T–41 DTC
TABLE.)
2. Referring to the following table, determine the malfunctioning part of the CAN system.
X: Normal
—: Communication error
Instrument Cluster
1. Access and monitor the “PCM_MSG”, “ABS_MSG”, “AWD_MSG” and “TCM_MSG” of PID using the SST
(WDS or equivalent).
2. Referring to the PID/DATA MONITOR, confirm the display status of the PID. (See T–41 PID/DATA MONITOR
TABLE.)
3. Referring to the following table, determine the malfunctioning part of the CAN system.
ModuleCommunication status
Malfunction location
PCM TCM4WD control
moduleInstrument cluster
•ABS
(ABS/
TCS) HU/
CM
•DSC HU/
CM————•Wiring harness D
•ABS (ABS/TCS)
HU/CM
•DSC HU/CM
—XXX•Wiring harness A
•PCM
X—XX•Wiring harness B
•TCM
XX—X•Wiring harness F
•4WD control
module
XXX—•Wiring harness G
•Instrument cluster
——XX•Wiring harness C
XX——•Wiring harness E
ModuleCommunication status
Malfunction location
PCM TCMABS (ABS/TCS) HU/CM
DSC HU/CM
4WD
control
module———•Wiring harness E
•Wiring harness F
•4WD control module
—XX•Wiring harness A
•PCM
X—X•Wiring harness B
•TCM
XX—•Wiring harness D
•ABS (ABS/TCS) HU/CM
•DSC HU/CM
——X•Wiring harness C

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
T–45
T
2WD
X: Normal
—: Communication error
4WD
X: Normal
—: Communication error
End Of SieDTC U0073, U1900, U2516A6E816255430205
ModuleCommunication status
Malfunction location
PCMABS (ABS/TCS) HU/CM
DSC HU/CM
Instrument cluster——•Wiring harness C
•Instrument cluster
—X•Wiring harness A
•PCM
X—•Wiring harness B
•ABS (ABS/TCS) HU/CM
•DSC HU/CM
ModuleCommunication status
Malfunction location
PCM TCMABS (ABS/TCS)
HU/CM
DSC HU/CM4WD control
module
Instrument
cluster————•Wiring harness G
•Instrument cluster
—XXX•Wiring harness A
•PCM
X—XX•Wiring harness B
•TCM
XX—X•Wiring harness D
•ABS (ABS/TCS)
HU/CM
•DSC HU/CM
XXX—•Wiring harness F
•4WD control
module
——XX•Wiring harness C
———X•Wiring harness E
DTCU0073
CAN system communication error
U1900
U2516 CAN system wiring harness open and short circuit
DETECTION
CONDITIONWarning
•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, TCM, ABS (ABS/TCS) HU/CM or DSC HU/CM, 4WD control
module and Instrument cluster
•PCM malfunction
•TCM malfunction
•ABS (ABS/TCS) HU/CM malfunction (with ABS (ABS/TCS))
•DSC HU/CM malfunction (with DSC)
•4WD control module malfunction
•Instrument cluster malfunction

T–46
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
Diagnostic procedure
STEP INSPECTION ACTION
1 Is inspected vehicle 2WD? Yes Go to next step.
No Go to Step 18.
2DETERMINING THE LOCATION OF A
MALFUNCTION
•Determine the malfunctioning part of the
CAN system.
(See T–42 PROCEDURES FOR
DETERMINING THE LOCATION OF A
MALFUNCTION)
•Is the malfunctioning part the wiring harness
C or the instrument cluster?Yes Go to Step 5.
No Go to next step.
3DETERMINING 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 9.
No Go to next step.
4DETERMINING THE LOCATION OF A
MALFUNCTION
•Is the malfunctioning part the wiring harness
A or the PCM?Yes Go to Step 13.
No Go to next step.
PCMWIRING
HARNESS A
TWIST PAIRWIRING
HARNESS BWIRING
HARNESS C
INSTRUMENT
CLUSTER ABS (ABS/TCS)
HU/CM
OR
DSC HU/CM
TCM4WD
CONTROL
MODULE
WIRING
HARNESS EWIRING
HARNESS G
WIRING
HARNESS D
WIRING
HARNESS F
PCMWIRING
HARNESS A
INSTRUMENT
CLUSTER ABS (ABS/TCS)
HU/CM
OR
DSC HU/CM
WIRING
HARNESS C
WIRING
HARNESS B
2WD
4WD

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
T–47
T
5INSPECT INSTRUMENT CLUSTER
CONNECTOR
•Disconnect negative battery cable.
•Disconnect instrument cluster connector.
•Are poor connection detection bars of
instrument cluster connector okay?Yes Go to next step.
No Replace wiring harness.
6•Is vehicle equipped with DSC? Yes Go to next step.
No Go to step 8.
7INSPECT WIRING HARNESS BETWEEN DSC
HU/CM AND INSTRUMENT CLUSTER
•Disconnect DSC HU/CM connector.
•Inspect the 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 17.
No Replace wiring harness.
8INSPECT WIRING HARNESS BETWEEN ABS
(ABS/TCS) HU/CM AND INSTRUMENT
CLUSTER
•Disconnect ABS (ABS/TCS) HU/CM
connector.
•Inspect the 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 17.
No Replace wiring harness.
9INSPECT 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 the connector for the ABS (ABS/TCS) HU/
CM or DSC HU/CM connected correctly?Yes Go to next step.
No Replace wiring harness.
10•Is vehicle equipped with DSC? Yes Go to next step.
No Go to step 12.
11INSPECT WIRING HARNESS BETWEEN DSC
HU/CM AND INSTRUMENT CLUSTER
•Disconnect DSC HU/CM connector.
•Inspect the 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 17.
No Replace wiring harness.
12INSPECT WIRING HARNESS BETWEEN ABS
(ABS/TCS) HU/CM AND INSTRUMENT
CLUSTER
•Disconnect ABS (ABS/TCS) HU/CM
connector.
•Inspect the 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 17.
No Replace wiring harness.
13INSPECT PCM CONNECTOR
•Disconnect negative battery cable.
•Disconnect TCM connector.
•Is the connector for the TCM connected
correctly?Yes Go to next step.
No Replace wiring harness. STEP INSPECTION ACTION

T–48
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
14•Is vehicle equipped with DSC? Yes Go to next step.
No Go to step 16.
15INSPECT WIRING HARNESS BETWEEN PCM
AND DSC HU/CM
•Disconnect DSC HU/CM connector.
•Inspect the following wiring harness between
PCM and DSC HU/CM terminals for short to
ground, short power supply, and open circuit:
Except MZR-CD (RF Turbo)
—2R—AF (CAN_L)
—2U—AG (CAN_H)
MZR-CD (RF Turbo)
—39—AF (CAN_L)
—13—AG (CAN_H)
•Is wiring harness okay?Yes Replace PCM, then go to Step 17.
No Replace wiring harness.
16INSPECT WIRING HARNESS BETWEEN PCM
AND ABS (ABS/TCS) HU/CM
•Disconnect ABS (ABS/TCS) HU/CM
connector.
•Inspect the following wiring harness between
PCM and ABS (ABS/TCS) HU/CM terminals
for short to ground, short power supply, and
open circuit:
Except MZR-CD (RF Turbo)
—2R—R (CAN_L)
—2U—O (CAN_H)
MZR-CD (RF Turbo)
—39—R (CAN_L)
—13—O (CAN_H)
•Is wiring harness okay?Yes Replace PCM, then go to Step 28.
No Replace wiring harness.
17CHECK 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 2.
No Troubleshooting completed.
18DETERMINING THE LOCATION OF A
MALFUNCTION
•Determine the malfunctioning part of the
CAN system.
(See T–42 PROCEDURES FOR
DETERMINING THE LOCATION OF A
MALFUNCTION)
•Is the malfunctioning part the wiring harness
G or the instrument cluster?Yes Go to Step 25.
No Go to next step.
19DETERMINING THE LOCATION OF A
MALFUNCTION
•Is the malfunctioning part the wiring harness
F or the 4WD control module?Yes Go to Step 27.
No Go to next step.
20DETERMINING THE LOCATION OF A
MALFUNCTION
•Is the malfunctioning part the wiring harness
E?Yes Go to Step 29.
No Go to next step.
21DETERMINING THE LOCATION OF A
MALFUNCTION
•Is the malfunctioning part the wiring harness
D or the ABS (ABS/TCS) HU/CM? (with ABS
(ABS/TCS))
•Is the malfunctioning part the wiring harness
D or the DSC HU/CM? (with DSC)Yes Go to Step 32.
No Go to next step. STEP INSPECTION ACTION