2002 MAZDA 6 key

M–16
ELECTRONIC 4WD CONTROL SYSTEM
ON-BOARD DIAGNOSTICA6E632227100208Outline
•The on-board diagnostic function allows for detecting malfunctions in the input/output signals when the ignition
key is at the ON position.
•The DLC-2, which combines the failure detection and detection maintenance connectors, has been adopted to
improve serviceability. By connecting a WDS or equivalent to the DLC-2, malfunction diagnosis can be carried
out.
•Using a WDS or equivalent DTCs can be retrieved or erased, depending on the screen display, thus improving
serviceability.
Block diagram
.
Self-diagnostic function
Failure detection function
•The failure detection function detects malfunctions in the input/output signal systems of the 4WD CM and
displays them when the ignition key is at the ON position.
•When the ignition key is turned to the ON position, the 4WD CM system begins operation, and the 4WD
warning light illuminates for 3 seconds while the function checks for open circuits. At the same time the function
monitors the condition of the power supply voltage and checks for internal malfunctions.
•Then, once the system is running, the function checks the operating conditions of the 4WD solenoid and the
differential oil temperature sensor at regular intervals to determine whether there is any malfunction.
•If any malfunction is detected during these diagnostic tests, the warning light illuminates according to the
malfunction to alert the driver. Also, a DTC is output to DLC-2 via the CAN line. Also, at the same time the
failure detection result is sent to the memory and fail-safe functions.
9
87
5
4
3
10
13
11
12
6
12
A6E63222010
1 Input part
2 Regular control area
3 Output part
4 Fail-safe function
5 Failure detection function
6 Memory function
7 Failure display function8 External tester communication function
9 Failure diagnosis function
10 4WD warning light
11 DLC-2
12 CAN
13 WDS or equivalent

ELECTRONIC 4WD CONTROL SYSTEM
M–17
M
Memory function
•This function stores DTCs for malfunctions of the input/output signal systems as determined by the failure
detection function. Once a DTC is stored, it is not cleared even if the input/output signal system malfunction
returns to normal when the ignition key is turned to the LOCK position (engine OFF).
•Since DTCs are stored in the non-volatile memory inside the 4WD CM, they are not cleared even if the battery
is disconnected. Therefore, it is necessary to clear the memory when maintenance has been completed. For
clearing DTCs, refer to the procedures in the Workshop Manual.
•When inspecting DTCs using a WDS or equivalent, only one memory stored DTC at a time can be displayed.
Therefore, when multiple DTCs have been stored, it is necessary to inspect for DTCs again after repairing and
clearing the present DTC to ensure that there are no more DTCs present in the memory.
Fail-safe function
•When the failure detection function determines that there is a malfunction, the 4WD warning light illuminates to
alert the driver. At this time, the fail-safe function suspends control or takes other measures to ensure that
driving stability is not lost.
X:Available
*1: Does not illuminate when only the coupling torque request signal from the DSC HU/CM cannot be received.*2: Only integrated DSC control is prohibited when only the coupling torque request signal from the DSC HU/CM
cannot be received.
External tester communication function
•This function allows for the storing and clearing of DTCs due to a communication link between the 4WD CM
and an external tester.
End Of Sie
DTC Malfunction location4WD warning
lightconditionDTC stored in
memoryControl condition
P1887 System wiring Illuminated X Stop
P1888 Differential oil temperature sensor Illuminated X Stop
U0100 PCM communication system Illuminated X Stop
U0101 TCM communication system Illuminated X Stop
U0121 DSC communication system
Illuminated
*1X
Stop*2

M–66
ELECTRONIC 4WD CONTROL SYSTEM
4WD SOLENOID INSPECTIONA6E6322271002111. Disconnect the negative (-) battery cable.
2. Disconnect the 4WD solenoid connector.
3. Measure resistance between 4WD solenoid
connector terminals A and B.
•If the resistance is not within the specification,
replace the coupling unit.
Resistance
1.5—2.0 ohms
(Rear differential oil temperature at 20°C
{68°F})
4. Connect the 4WD solenoid connector.
5. Connect the negative (-) battery cable.
End Of Sie
4WD CONTROL MODURE INSPECTIONA6E632227100212
Note
•4WD CM terminal voltage can vary depending on measuring conditions and vehicle aging, resulting in
misdiagnosis. Therefore, it is necessary to perform an overall inspection of the input/output systems and
4WD CM to determine which part is malfunctioning.
•With the 4WD CM connector connected, measure voltage by connecting the voltmeter negative (-) lead to
the body ground and positive (+) lead to each 4WD CM terminal.
1. Measure voltage or resistance at each 4WD CM terminal using a voltmeter and an ohmmeter.
•If not as specified, replace the 4WD CM.
Terminal Voltage List (Reference)
A
B
A6J63222103
Terminal SignalInput/
outputConnected
toMeasuring
itemTest conditionVoltage (V)/
ContinuityInspection location
in case of failure
ADifferential oil
temperature
sensor signalInputDifferential oil
temperature
sensorVoltageIgnition
key
ONDifferential oil
temperature
20°C {68°F}3.0•Inspect
differential oil
temperature
sensor
•Inspect related
harness Differential oil
temperature
60°C {140°F}1.4
B——— ——— — —
CDifferential oil
temperature
sensor GND—Differential oil
temperature
sensorContinuity Any condition Yes•Inspect related
harness
D——— ——— — —
E——— ——— — —
F——— ——— — —
GCAN-HInput/
output—Perform measurement during DTC inspection.—
HCAN-LInput/
output—Perform measurement during DTC inspection.—
A
B C
D E
F G
H I
J K
L M
N O
P
A6J63222104

ELECTRONIC 4WD CONTROL SYSTEM
M–67
M
End Of Sie
4WD CONTROL MODURE REMOVAL/INSTALLATIONA6E6322271002131. Disconnect the negative (-) battery cable.
2. Remove the lower panel.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
.
End Of Sie
IPower supply
(Ignition
switch)Input Ignition key VoltageIgnition key ON B+•Inspect fuse
•Inspect related
harness Ignition key OFF 1.0 or below
J——— ——— — —
KPower supply
(Main)Input Battery Voltage Any condition B+•Inspect fuse
•Inspect related
harness
L——— ——— — —
M——— ——— — —
N Ground—Ground Voltage Any condition 0•Inspect related
harness
O4WD solenoid
(+)Output 4WD solenoid VoltageIgnition key ON B+•4WD solenoid
•Inspect related
harness Ignition key OFF 1.0 or below
P4WD solenoid
(-)Output 4WD solenoid VoltageIgnition key ON B+•4WD solenoid
•Inspect related
harness Ignition key OFF 1.0 or below Terminal SignalInput/
outputConnected
toMeasuring
itemTest conditionVoltage (V)/
ContinuityInspection location
in case of failure
31
2
31
2
7.8—10.8 {0.8—1.1, 5.6—7.9}
N·m {kgf·m, ft·lbf} 7.8—10.8 {0.8—1.1, 5.6—7.9}
L.H.D.
R.H.D.
A6E63222105
1 Connector
2Nut34WD CM

M–76
ON-BOARD DIAGNOSTIC
ELECTRONIC 4WD CONTROL SYSTEM ON-BOARD DIAGNOSISA6E637027100202Reading DTCs Procedure
1. Connect WDS or equivalent to the vehicle DLC-2
16-pin connector.
2. Retrieve DTC by WDS or equivalent.
•If a DTC is displayed, proceed with inspection
steps for that DTC.
3. After repair, clear DTCs stored in the 4WD CM by
referring to the Clearing DTCs Procedure.
Clearing DTCs Procedures
1. Connect WDS or equivalent to the vehicle DLC-2
16-pin connector.
2. Clear DTCs by WDS or equivalent.
3. Turn the ignition key to OFF.
4. Perform the DTC inspection again, and verify that
no DTC appears.
5. Disconnect the WDS or equivalent.
DTC Table
End Of Sie
DLC-2
DLC-2
L.H.D.
R.H.D.
A6E63702005
DLC-2
DLC-2
L.H.D.
R.H.D.
A6E63702005
DTC
Diagnosis system component Page
WDS or equivalent
P1887 System wiring (See M–77 DTC P1887)
P1888 Differential oil temperature sensor (See M–79 DTC P1888)
U0100 PCM communication (See M–80 DTC U0100)
U0101 TCM communication (See M–80 DTC U0101)
U0121 ABS/DSC communication (See M–80 DTC U0121)

ON-BOARD DIAGNOSTIC
M–77
M
DTC P1887A6E637027100203
Diagnostic procedure
DTC P1887 System wiring
DETECTION
CONDITION•Current detection circuit in 4WD CM detects current above specification for more than specified period.
•4WD CM detects that 4WD solenoid control signal differs from current detected at current detection
circuit for more than specified period.
•Relay voltage detection circuit detects that voltage does not concur with relay ON/OFF signal for more
than specified period.
POSSIBLE
CAUSE•Open circuit or short to GND in harness between battery and 4WD CM terminal K
•Open circuit or short to GND between 4WD CM terminal O and 4WD solenoid terminal B
•Open circuit between 4WD CM terminal P and 4WD solenoid terminal A
•Open circuit between 4WD CM terminal N and body GND
•Open or short circuit in 4WD CM internal circuit
•ENG+B (10A) fuse malfunction
•4WD solenoid malfunction
•4WD CM malfunction
•Poor connection of connectors (female terminals)
STEP INSPECTION ACTION
1INSPECT 4WD SOLENOID CONDITION
•Turn ignition key to OFF.
•Disconnect 4WD solenoid connector.
•Inspect 4WD solenoid.
(See M–66 4WD SOLENOID INSPECTION)
•Is it okay?Yes Go to next step.
No Replace 4WD solenoid, then go to Step 9.
2INSPECT 4WD SOLENOID TO 4WD CM
(POWER SUPPLY CIRCUIT) FOR OPEN
CIRCUIT
•Disconnect 4WD CM connector.
•Inspect for continuity between 4WD CM
terminal O and 4WD solenoid terminal B.
•Is there continuity?Yes Go to next step.
No Repair or replace harness for open circuit between 4WD CM
and 4WD solenoid, then go to Step 9.
A A
B C
D E
F G
H I
J K
L M
N O
PB K
O B
A
N P BATTERYFUSE (ENG+B 10 A)
4WD CM
4WD CM CONNECTOR4WD SOLENOID
4WD SOLENOID CONNECTOR RELAY

M–78
ON-BOARD DIAGNOSTIC
End Of Sie
3INSPECT 4WD SOLENOID TO 4WD CM
(POWER SUPPLY CIRCUIT) FOR SHORT TO
GROUND
•Inspect for continuity between 4WD CM
terminal O and ground.
•Is there continuity?Yes Repair or replace harness for short to ground between 4WD
CM and 4WD solenoid, then go to Step 9.
No Go to next step.
4INSPECT 4WD SOLENOID TO 4WD CM
(GROUND CIRCUIT) FOR OPEN CIRCUIT
•Inspect for continuity between 4WD CM
terminal P and 4WD solenoid terminal A.
•Is there continuity?Yes Replace 4WD CM, then go to next step.
No Repair or replace harness for open circuit between 4WD CM
and 4WD solenoid, then go to Step 9.
5INSPECT 4WD CM POWER SUPPLY CIRCUIT
FOR OPEN CIRCUIT
•Measure voltage between 4WD CM terminal
K and ground.
•Is voltage B+?Yes Replace 4WD CM, then go to Step 9.
No Go to next step.
6INSPECT 4WD CM TO BATTERY FOR OPEN
CIRCUIT
•Disconnect 4WD CM connector and battery
positive terminal.
•Inspect for continuity between 4WD CM
terminal K and battery positive terminal.
•Is there continuity?Yes Go to next step.
No Repair or replace harness for open circuit between 4WD CM
and battery positive terminal, then go to Step 9.
7INSPECT 4WD CM TO BATTERY FOR SHORT
TO GROUND
•Inspect for continuity between 4WD CM
terminal K and ground.
•Is there continuity?Yes Repair or replace harness for short to ground between 4WD
CM and battery positive terminal, then go to Step 9.
No Replace 4WD CM, then go to step 9.
8INSPECT FUSE CONDITION
•Turn ignition key to OFF.
•Is ENG+B fuse (10A) okay?Yes Go to next step.
No Replace fuse, then go to Step 9.
9VERIFY TROUBLESHOOTING COMPLETED
•Make sure to reconnect all disconnected
connectors.
•Clear DTC from memory.
(See M–76 Clearing DTCs Procedures)
•Drive vehicle.
•Is the same DTC present?Yes Replace 4WD CM, then go to next step.
No Go to next step.
10VERIFY AFTER REPAIR PROCEDURE
•Is there any other DTC present?Yes Go to applicable DTC inspection.
No Troubleshooting completed. STEP INSPECTION ACTION

ON-BOARD DIAGNOSTIC
M–79
M
DTC P1888A6E637027100204
Diagnostic procedure
DTC P1888 Differential oil temperature sensor
DETECTION
CONDITION•Differential oil temperature sensor voltage monitor circuit detects abnormal input voltage.
POSSIBLE
CAUSE•Open circuit, or short to battery or GND between 4WD CM terminal A and differential oil temperature
sensor terminal A
•Open circuit or short to battery between 4WD CM terminal C and differential oil temperature sensor
terminal B
•Differential oil temperature sensor malfunction
•4WD CM malfunction
•Poor connection of connectors (female terminals)
STEP INSPECTION ACTION
1INSPECT DIFFERENTIAL OIL
TEMPERATURE SENSOR CONDITION
•Turn ignition key to OFF.
•Disconnect differential oil temperature
sensor connector.
•Is it okay?Yes Go to next step.
No Replace differential oil temperature sensor, then go to Step
7.
2INSPECT 4WD CM TO DIFFERENTIAL OIL
TEMPERATURE SENSOR FOR OPEN
CIRCUIT
•Disconnect 4WD CM connector.
•Inspect for continuity between 4WD CM
terminal A and differential oil temperature
sensor terminal A.
•Is there continuity?Yes Go to next step.
No Repair or replace harness for open circuit between 4WD CM
and differential oil temperature sensor, then go to Step 7.
3INSPECT 4WD CM TO DIFFERENTIAL OIL
TEMPERATURE SENSOR FOR SHORT TO
POWER
•Inspect voltage between 4WD CM terminal A
and ground.
•Is voltage B+?Yes Repair or replace harness for short to power between 4WD
CM and differential oil temperature sensor, then go to Step
7.
No Go to next step.
A B A
B C
D E
F G
H I
J K
L M
N O
PA
C A
B
4WD CM CONNECTOR4WD CM
DIFFERENTIAL OIL
TEMPERATURE SENSOR
DIFFERENTIAL OIL TEMPERATURE
SENSOR CONNECTOR