2002 MAZDA 6 4WD

M–14
ELECTRONIC 4WD CONTROL SYSTEM
End Of Sie4WD SYSTEM CONTROLA6E632227100206Outline
Features
•Based on the inputted signals listed below, the 4WD CM calculates the optimal amount of torque distribution for
the rear wheels and outputs a corresponding electric control current to the electronic control coupling (4WD
solenoid).
•The module controls the current outputted to the 4WD solenoid by changing the rate of the ON/OFF timing.
Construction
Block diagram
.
Signal output part Signal name Note
PCMThrottle opening angle
Engine speed
Transmitted as a CAN signal TCMSelector lever position
Gear position
DSC HU/CMFour-wheel speed
DSC operating condition
Coupling torque request (DSC equipped vehicles)
Differential oil temperature
sensorRear differential oil temperature—
9
87
5
4
310
1413
11
12
61
2
A6E63222009
1PCM
2TCM
3 DSC HU/CM
4 Differential oil temperature sensor
5 Throttle opening angle
6 Engine speed
7 Selector lever position8 Gear position
9 Four-wheel speed
10 DSC operating condition
11 Coupling torque request (DSC equipped vehicles)
12 Rear differential oil temperature
13 4WD control modure (4WD CM)
14 Electronic control coupling (4WD solenoid)

ELECTRONIC 4WD CONTROL SYSTEM
M–15
M
Operation
Normal control
•When starting off or accelerating during straight-ahead driving, torque transmitted to the rear wheels is
optimally controlled to ensure sufficient acceleration performance. Due to this, standing-start and acceleration
performance is improved.
•Also, in order to improve fuel economy when driving at a stable, consistent speed, torque transmitted to the
rear wheels is damped, and rear-wheel drive is controlled to maintain it close to that of the front wheels.
Tight cornering control
•When the 4WD CM determines, based on the four-wheel speed signal, that the vehicle is in tight cornering, it
reduces the torque transmitted to the rear wheels to avoid tight corner braking characteristics.
Integrated DSC control
•If a signal from the DSC HU/CM input to the 4WD CM indicates that ABS control is activated, the module
controls the torque transmitted to the rear wheels to prevent undue influence on ABS control.
•Also, when a coupling torque request signal is received from the DSC HU/CM, the module controls the torque
transmitted to the rear wheels to match the amount of requested torque.
Other control
•In case the rear differential oil temperature exceeds the specified amount, or when there is an unusually large
variation in the rotation speed of the front and rear wheels (ex. when trying to get unstuck), control is
temporarily suspended in order to protect the 4WD system. When this occurs the 4WD warning light flashes to
indicate the situation to the driver.
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CONTROLLER AREA NETWORK (CAN)A6E632227100207Outline
•The 4WD CM transmits/receives information using the CAN system. See Section T for detailed information
regarding the CAN system.
Operation
Transmitted information
•Coupling torque
•4WD system operating condition (warning light information)
Received information
•Four-wheel speed
•Throttle opening angle
•Engine speed
•ABS/DSC operating condition
•Gear position
•Selector lever position
•Coupling torque request
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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.
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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.
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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–18
OUTLINE
SUPPLEMENTAL SERVICE INFORMATIONA6E630201018204•The following additions have been made since publication of the Mazda6 Workshop Manual (1730-1*-02C).
Rear wheel hub bolt
•Replacement procedure has been added.
Wheel hub, knuckle
•Removal/installation procedure has been added.
Joint shaft (MZR-CD (RF Turbo))
•Disassembly/assembly procedure has been added.
Joint shaft (4WD)
•Disassembly/assembly procedure has been added.
Front drive shaft (MZR-CD (RF Turbo))
•Disassembly/assembly procedure has been added.
Front drive shaft (4WD)
•Disassembly/assembly procedure has been added.
Rear drive shaft
•Inspection procedure has been added.
•Removal/installation procedure has been added.
•Disassembly/assembly procedure has been added.
Differential oil
•Inspection procedure has been added.
•Replacement procedure has been added.
Oil seal (side gear)
•Replacement procedure has been added.
Oil seal (companion flange)
•Replacement procedure has been added.
Rear differential
•Removal/installation procedure has been added.
•Disassembly procedure has been added.
•Assembly procedure has been added.
Differential oil temperature sensor
•Inspection procedure has been added.
•Removal/installation procedure has been added.
4WD solenoid
•Inspection procedure has been added.
Coupling component
•Removal/installation procedure has been added.
•Disassembly procedure has been added.
•Assembly procedure has been added.
On-board diagnostic
•Electronic 4WD control system have been added.
Troubleshooting
•Electronic 4WD control system have been added.
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OUTLINE

LOCATION INDEX
M–19
M
AXLE/DRIVE SHAFT LOCATION INDEXA6E630025500201
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LOCATION INDEX
5
4
3
1
2
A6J63002001
1 Wheel hub bolt
(See M–22 WHEEL HUB BOLT REPLACEMENT)
2 Wheel hub, knuckle
(See M–22 WHEEL HUB, KNUCKLE REMOVAL/
INSTALLATION)
3 Joint shaft
(See M–29 JOINT SHAFT (MZR-CD (RF Turbo))
DISASSEMBLY/ASSEMBLY)
(See M–31 JOINT SHAFT (4WD) DISASSEMBLY/
ASSEMBLY)4 Front drive shaft
(See M–34 FRONT DRIVE SHAFT (MZR-CD (RF
Turbo)) DISASSEMBLY/ASSEMBLY)
(See M–39 FRONT DRIVE SHAFT (4WD)
DISASSEMBLY/ASSEMBLY)
5 Rear drive shaft
(See M–42 REAR DRIVE SHAFT
PRE-INSPECTION)
(See M–43 REAR DRIVE SHAFT REMOVAL/
INSTALLATION)
(See M–45 REAR DRIVE SHAFT DISASSEMBLY/
ASSEMBLY)

M–20
LOCATION INDEX
REAR DIFFERENTIAL/ELECTRONIC 4WD CONTROL SYSTEM LOCATION INDEXA6E630027100201
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7
5
4
3
6
1
2
8
7
5
4
3
6
1
2
L.H.D.
R.H.D.
A6J63002002
1 Differential oil
(See M–48 DIFFERENTIAL OIL INSPECTION)
(See M–48 DIFFERENTIAL OIL REPLACEMENT)
2 Oil seal (side gear)
(See M–49 OIL SEAL (SIDE GEAR)
REPLACEMENT)
3 Oil seal (companion flange)
(See M–49 OIL SEAL (COMPANION FLANGE)
REPLACEMENT)
4 Rear differential
(See M–51 REAR DIFFERENTIAL REMOVAL/
INSTALLATION)
(See M–52 REAR DIFFERENTIAL DISASSEMBLY)
(See M–56 REAR DIFFERENTIAL ASSEMBLY)5 Differential oil temperature sensor
(See M–65 DIFFERENTIAL OIL TEMPERATURE
SENSOR INSPECTION)
(See M–65 DIFFERENTIAL OIL TEMPERATURE
SENSOR REMOVAL/INSTALLATION)
6 4WD solenoid
(See M–66 4WD SOLENOID INSPECTION)
7 4WD control module
(See M–66 4WD CONTROL MODURE
INSPECTION)
(See M–67 4WD CONTROL MODURE REMOVAL/
INSTALLATION)
8 Coupling component
(See M–68 COUPLING COMPONENT REMOVAL/
INSTALLATION)
(See M–69 COUPLING COMPONENT
DISASSEMBLY)
(See M–72 COUPLING COMPONENT
ASSEMBLY)

GENERAL PROCEDURES
M–21
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PRECAUTION (FRONT AND REAR AXLE)A6E631001018201Wheel and Tire Removal/Installation
1. The removal and installation procedures for the wheels and tires are not mentioned in this section. When a
wheel is removed, tighten it to 88—118 N·m {9.0—12.0 kgf·m, 65.0—87.0 ft·lbf}
Brake Line Disconnection/Connection
Caution
•Brake fluid will damage painted surfaces. If brake fluid gets on a painted surface, wipe it off
immediately.
1. Tighten the brake pipe flare nut using the SST (49 0259 770B). Be sure to modify the brake pipe flare nut
tightening torque to allow for use of a torque wrench-SST combination.
2. If any brake line has been disconnected any time during the procedure, add brake fluid, bleed the brakes, and
inspect for leakage after the procedure has been completed.
Suspension Arm Removal/Installation
1. Tighten any part of the suspension that uses rubber bushings only after vehicle has been lowered and
unloaded.
Note
•Unloaded: Fuel tank is full. Engine coolant and engine oil are at specified level. Spare tire, jack, and tools
are in designated position.
Connector Disconnection
1. Disconnect the negative (-) battery cable before disconnecting connectors.
Electronic Control 4WD System Parts
1. After servicing the electronic control 4WD system parts, verify that no DTC has been stored. Clear any DTCs
remaining in the memory.
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GENERAL PROCEDURES