Page 2817 of 4555
ALL MODE 4X4 SYSTEM
TF-13
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System DiagramEDS001VC
Large difference in diameter of front/rear tiresSlow flashing: 1 time/2 seconds
(Continuing to flash until turning ignition switch OFF)
Other than above (system normal) OFFCondition 4WD warning lamp
SDIA1866E
Page 2818 of 4555

TF-14
ALL MODE 4X4 SYSTEM
COMPONENTS FUNCTION DESCRIPTION
CAN CommunicationEDS0027K
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only.
CAN Communication UnitEDS002XA
Component parts Function
4WD control unit
Controls driving force distribution by signals from each sensor and switch from front wheel driving
mode (100:0) to 4WD mode (50:50).
2WD mode is available by fail-safe function if malfunction is detected in electrical system.
Wheel sensors Detects wheel speed.
4WD solenoid Controls electric controlled coupling by operation signal from 4WD control unit.
Electric controlled coupling Transmits driving force to rear final drive.
4WD mode switch Able to select from 2WD, AUTO or LOCK mode.
4WD warning lamp
Illuminates if malfunction is detected in electrical system of 4WD system.
There is 1 blink in 2 seconds if rotation difference of front wheels and rear wheels is large.
There are 2 blinks in 1 second if load is still applied to driving parts.
4WD indicator lamp Indicate operation with optimal distribution of torque to front/rear wheels.
LOCK indicator lamp Indicate that 4WD system is under direct 4-wheel driving mode.
ABS actuator and electric unit
(control unit) (without ESP) or
ESP/TCS/ABS control unit (with
ESP)Transmits the following signals via CAN communication to 4WD control unit.
Vehicle speed signal
Stop lamp switch signal (brake signal)
ECMTransmits the following signals via CAN communication to 4WD control unit.
Accelerator pedal position signal
Engine speed signal
Unified meter control unit Transmits conditions of parking brake switch via CAN communication to 4WD control unit.
Body typeWagon
Axle4WD
Engine YD22DDTi QR20DE/QR25DE YD22DDTi QR25DE
Transmission M/T A/T M/T A/T
Brake control ABS ESP
CAN system type 123456
Page 2819 of 4555
ALL MODE 4X4 SYSTEM
TF-15
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TYPE 1/TYPE 2
System diagram
Input/output signal chart
T: Transmit R: Receive
*: YD engine models only
PKIA6458E
Signals ECMABS actuator and
electric unit
(control unit)4WD control unit Combination meter
4WD mode indicator lamp signal T R
4WD warning lamp signalTR
A/C compressor feedback signal T R
ABS warning lamp signal T R
Accelerator pedal position signal T R
Engine coolant temperature signal T R
Engine speed signal T R R
MI signal T R
Parking brake switch signalRT
Stop lamp switch signal T R
Vehicle speed signalTRR
RT
ASCD SET lamp signal T R
Stop lamp switch signal T R
Glow indicator lamp signal* T R
A/C switch signal* R T
Page 2820 of 4555
TF-16
ALL MODE 4X4 SYSTEM
TYPE 3
System diagram
Input/output signal chart
T: Transmit R: Receive
PKIA6457E
Signals ECM TCMABS actuator
and electric unit
(control unit)4WD control
unitCombination
meter
4WD mode indicator lamp signalTR
4WD warning lamp signalTR
A/C compressor feedback signal TR
A/T position indicator lamp signal T R
A/T self-diagnosis signal R T
ABS warning lamp signal T R
Accelerator pedal position signal T R
Closed throttle position signal T R
Engine A/T integrated control signalTR
RT
Engine coolant temperature signal TR
Engine speed signal T R R
MI signal TR
O/D OFF indicator signal T R
Output shaft revolution signal R T
Overdrive control switch signal R T
P·N range signal R T
Parking brake switch signalRT
Stop lamp switch signalRT
TR
Vehicle speed signalTRR
RT
Wide open throttle position signal T R
Page 2821 of 4555
ALL MODE 4X4 SYSTEM
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TYPE 4/TYPE 5
System diagram
Input/output signal chart
T: Transmit R: Receive ASCD SET lamp signal TR
ASCD CRUISE lamp signal TR Signals ECM TCMABS actuator
and electric unit
(control unit)4WD control
unitCombination
meter
PKIA9634E
Signals ECMESP/TCS/ABS
control unitSteering angle
sensor4WD control
unitCombination
meter
4WD mode indicator lamp signalTR
4WD warning lamp signalTR
A/C compressor feedback signal*
2TR
A/C switch signal*
1RT
ABS warning lamp signal T R
Accelerator pedal position signal T R R
Brake warning lamp signal T R
Engine coolant temperature signal TR
Engine speed signal T R R R
ESP OFF indicator lamp signal T R
Glow indicator lamp signal*1 TR
MI signal TR
Stop lamp switch signal T R
Vehicle speed signalTRR
RT
SLIP indicator lamp signal T R
Parking brake switch signalRT
Steering angle sensor signal R T
ASCD SET lamp signal TR
ASCD CRUISE lamp signal TR
Page 2822 of 4555
TF-18
ALL MODE 4X4 SYSTEM
*1: YD engine models only
*2: QR engine models only
TYPE 6
System diagram
Input/output signal chart
T: Transmit R: Receive
PKIA9635E
Signals ECM TCMESP/TCS/
ABS control
unitSteering
angle sensor4WD control
unitCombination
meter
4WD mode indicator lamp signalTR
4WD warning lamp signalTR
A/C compressor feedback signal TR
A/T position indicator lamp signal T R R
A/T self-diagnosis signal R T
ABS warning lamp signal T R
Accelerator pedal position signal T R R
Brake warning lamp signal T R
Closed throttle position signal T R
Engine and A/T integratedTR
RT
Engine coolant temperature signal TR
Engine speed signal T R R R
ESP OFF indicator lamp signal T R
MI signal TR
O/D OFF indicator signal T R
Output shaft revolution signal R T
Overdrive control switch signal R T
P·N range signal R T
SLIP indicator lamp signal T R
Steering angle sensor signal R T
Page 2823 of 4555
ALL MODE 4X4 SYSTEM
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Stop lamp switch signalRT
TR
Vehicle speed signalTRR
RT
Parking brake switch signalRT
Wide open throttle position signal T R
ASCD SET lamp signal TR
ASCD CRUISE lamp signal TR Signals ECM TCMESP/TCS/
ABS control
unitSteering
angle sensor4WD control
unitCombination
meter
Page 2824 of 4555

TF-20
TROUBLE DIAGNOSIS
TROUBLE DIAGNOSISPFP:00004
Fail-Safe FunctionEDS001VE
If any malfunction occurs in 4WD electrical system, and control unit detects the malfunction, 4WD warning
lamp on combination meter turns ON to indicate system malfunction.
When 4WD warning lamp is ON, vehicle changes to front-wheel drive or shifting driving force-4WD (Rear-
wheels still have some driving torque).
How to Perform Trouble DiagnosisEDS001VF
BASIC CONCEPT
To perform trouble diagnosis, it is the most important to have understanding about vehicle systems (con-
trol and mechanism) thoroughly.
It is also important to clarify customer complaints before inspec-
tion.
First of all, reproduce symptoms, and understand them fully.
Ask customer about his/her complaints carefully. In some cases,
it will be necessary to check symptoms by driving vehicle with
customer.
CAUTION:
Customers are not professional. It is dangerous to make an
easy guess like "maybe the customer means that...," or
"maybe the customer mentions this symptom".
It is essential to check symptoms right from the beginning in
order to repair malfunctions completely.
For intermittent malfunctions, reproduce symptoms based on
interview with customer and past examples. Do not perform
inspection on ad hoc basis. Most intermittent malfunctions are
caused by poor contacts. In this case, it will be effective to shake
suspected harness or connector by hand. When repairing with-
out any symptom diagnosis, you cannot judge if malfunctions
have actually been eliminated.
After completing diagnosis, always erase diagnostic memory.
Refer to TF-33, "
How to Erase Self-diagnostic Results" .
For intermittent malfunctions, move harness or harness connec-
tor by hand. Then check for poor contact or reproduced open circuit.
SEF233G
SEF234G