2002 MAZDA 6 ABS

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

T–50
ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
31INSPECT WIRING HARNESS BETWEEN ABS
(ABS/TCS) HU/CM AND 4WD CONTROL
MODULE
•Disconnect ABS (ABS/TCS) HU/CM
connector.
•Inspect the following wiring harness between
ABS (ABS/TCS) HU/CM and 4WD control
module terminals for short to ground, short
power supply, and open circuit:
—R—H (CAN_L)
—O—G (CAN_H)
•Is wiring harness okay?Yes Go to Step 45.
No Replace wiring harness.
32INSPECT 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.
33•Is vehicle equipped with DSC? Yes Go to next step.
No Go to step 35.
34INSPECT WIRING HARNESS BETWEEN DSC
HU/CM AND 4WD CONTROL MODULE
•Disconnect DSC HU/CM connector.
•Inspect the following wiring harness between
DSC HU/CM and 4WD control module
terminals for short to ground, short power
supply, and open circuit:
—AF—H (CAN_L)
—AG—G (CAN_H)
•Is wiring harness okay?Yes Replace DSC HU/CM, then go to Step 45.
No Replace wiring harness.
35INSPECT WIRING HARNESS BETWEEN ABS
(ABS/TCS) HU/CM AND 4WD CONTROL
MODULE
•Disconnect ABS (ABS/TCS) HU/CM
connector.
•Inspect the following wiring harness between
ABS (ABS/TCS) HU/CM and 4WD control
module terminals for short to ground, short
power supply, and open circuit:
—R—H (CAN_L)
—O—G (CAN_H)
•Is wiring harness okay?Yes Replace ABS (ABS/TCS) HU/CM, then go to Step 45.
No Replace wiring harness.
36•Is vehicle equipped with DSC? Yes Go to next step.
No Go to step 38.
37INSPECT WIRING HARNESS BETWEEN TCM
AND DSC HU/CM
•Disconnect TCM connector.
•Inspect the following wiring harness between
TCM and DSC HU/CM terminals for short to
ground, short power supply, and open circuit:
—2J—AF (CAN_L)
—2M—AG (CAN_H)
•Is wiring harness okay?Yes Go to Step 45.
No Replace wiring harness.
38INSPECT WIRING HARNESS BETWEEN TCM
AND ABS (ABS/TCS) HU/CM
•Disconnect TCM connector.
•Inspect the following wiring harness between
TCM and ABS (ABS/TCS) HU/CM terminals
for short to ground, short power supply, and
open circuit:
—2J—R (CAN_L)
—2M—O (CAN_H)
•Is wiring harness okay?Yes Go to Step 45.
No Replace wiring harness. STEP INSPECTION ACTION

ON-BOARD DIAGNOSTIC [MULTIPLEX COMMUNICATION SYSTEM]
T–51
T
End Of Sie
39INSPECT TCM 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.
40•Is vehicle equipped with DSC? Yes Go to next step.
No Go to step 42.
41INSPECT WIRING HARNESS BETWEEN TCM
AND DSC HU/CM
•Disconnect DSC HU/CM connector.
•Inspect the following wiring harness between
TCM and DSC HU/CM terminals for short to
ground, short power supply, and open circuit:
—2J—AF (CAN_L)
—2M—AG (CAN_H)
•Is wiring harness okay?Yes Replace TCM, then go to Step 45.
No Replace wiring harness.
42INSPECT WIRING HARNESS BETWEEN TCM
AND ABS (ABS/TCS) HU/CM
•Disconnect ABS (ABS/TCS) HU/CM
connector.
•Inspect the following wiring harness between
TCM and ABS (ABS/TCS) HU/CM terminals
for short to ground, short power supply, and
open circuit:
—2J—R (CAN_L)
—2M—O (CAN_H)
•Is wiring harness okay?Yes Replace TCM, then go to Step 45.
No Replace wiring harness.
43INSPECT PCM CONNECTOR
•Disconnect negative battery cable.
•Disconnect PCM connector.
•Is the connector for the PCM connected
correctly?Yes Go to next step.
No Replace wiring harness.
44INSPECT WIRING HARNESS BETWEEN TCM
AND PCM
•Disconnect TCM connector.
•Inspect the following wiring harness between
TCM and PCM terminals for short to ground,
short power supply, and open circuit:
—2J—2R (CAN_L)
—2M—2U (CAN_H)
•Is wiring harness okay?Yes Replace PCM, then go to next step.
No Replace wiring harness.
45CHECK DTC INDICATE
•Connect PCM connector.
•Connect TCM connector.
•Connect ABS (ABS/TCS) HU/CM or DSC
HU/CM connector.
•Connect 4WD control module connector.
•Connect instrument cluster connector.
•Clear DTC from module memory using SST
(WDS or equivalent).
•Perform KOEO/KOER self-test.
•Are DTC’s U0073, U1900 and/or U2516
indicated?Yes Repeat from Step 18.
No Troubleshooting completed. STEP INSPECTION ACTION