ISUZU TROOPER 1998 Service Repair Manual

4B1±38
DRIVE LINE CONTROL SYSTEM (SHIFT ON THE FLY)
MEMO

4B2±1 DRIVE LINE CONTROL SYSTEM (TOD)
DRIVELINE/AXLE
DRIVELINE CONTROL SYSTEM (TOD)
CONTENTS
Service Precaution 4B2±1. . . . . . . . . . . . . . . . . . . . . .
General Description 4B2±2. . . . . . . . . . . . . . . . . . . . .
System Components 4B2±4. . . . . . . . . . . . . . . . . . . .
Parts Location 4B2±4. . . . . . . . . . . . . . . . . . . . . . . .
Functions of Indicator Lamp 4B2±8. . . . . . . . . . . . . .
Diagnosis 4B2±12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Basic Diagnostic Flow Chart 4B2±16. . . . . . . . . . . . . .
Parts Location 4B2±17. . . . . . . . . . . . . . . . . . . . . . . . . .
Circuit Diagram 4B2±18. . . . . . . . . . . . . . . . . . . . . . . . . Connector List 4B2±21. . . . . . . . . . . . . . . . . . . . . . . . . .
Checking Failed Pin 4B2±23. . . . . . . . . . . . . . . . . . . . .
Checking Failed TOD Control Unit Pin 4B2±26. . . . .
Diagnostic Trouble Codes 4B2±30. . . . . . . . . . . . . . . .
Diagnosis from Trouble Codes 4B2±31. . . . . . . . . . . .
Trouble Diagnosis Depending on The Status
of TOD Indicator 4B2±58. . . . . . . . . . . . . . . . . . . . . . . .
Diagnosis from Symptom 4B2±86. . . . . . . . . . . . . . . . .
Service Precaution
WARNING: I F S O E Q U IPPED WITH A
SUPPLEMENTAL RESTRAINT SYSTEM (SRS),
REFER TO THE SRS COMPONENT AND WIRING
LOCATION VIEW IN ORDER TO DETERMINE
WHETHER YOU ARE PERFORMING SERVICE ON OR
NEAR THE SRS COMPONENTS OR THE SRS
WIRING. WHEN YOU ARE PERFORMING SERVICE
ON OR NEAR THE SRS COMPONENTS OR THE SRS
WIRING, REFER TO THE SRS SERVICE
INFORMATION. FAILURE TO FOLLOW WARNINGS
COULD RESULT IN POSSIBLE AIR BAG
DEPLOYMENT, PERSONAL INJURY, OR
OTHERWISE UNNEEDED SRS SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (Paints, greases, or other
corrosion inhibitors) on threaded fasteners or
fastener joint interfaces. Generally, such coatings
adversely affect the fastener torque and the joint
clamping force, and may damage the fastener. When
you install fasteners, use the correct tightening
sequence and specifications. Following these
instructions can help you avoid damage to parts and
systems.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±2
General Description
C07RW014±1
TOD (Torque on Demand) system is traction state control
system to vehicle.
Transfer Position and Drive Mode
Three drive modes can be selected through operation of
4WD switch and transfer lever.
Transfer Position
TOD SWModeDrive mode
HIGHON (NORMAL)2HRear wheel drive
OFF (PUSHED)TODElectronically controlled torque split
four wheel drive
4LON/OFF4LLow-speed mechanical lock-up four
wheel drive
The electronic control unit (ECU) judges the signals from
the transfer lever and controls the transfer drive mode
and shift-on-the-fly system status.
TOD Control
The TOD position usually drives the rear wheels, and
transmits the torque to the front wheels with the help of
electronically controlled torque split mechanism
according to running conditions encountered. The driving
force is directly transmitted to the rear wheels. This force
is split by the transfer and delivered to the front wheels.
The magnitude of the torque transmitted to the front
wheels is controlled by changing the pressing force of the
electromagnetic multi plate disk clutch built in the transfer
unit. The pressing force of the clutch is controlled bychanging the voltage to the electromagnetic coil mounted
to the rear of the clutch. When the clutch is completely
disengaged, the rear wheels are driven. When the clutch
is completely engaged, a rigid four wheel drive mode is
obtained. The torque split status is controlled
continuously between the rear wheel and four wheel drive
modes. This system includes front and rear speed
sensors, and throttle position sensor that monitors the
engine output.
The control unit receives signals sent from these sensors
and changes the pressing force of the electromagnetic
multi plate disk clutch to determine the torque distribution
on the front and rear wheels. Therefore, when the slip of
the rear wheels is increased against the current torque
level in the normal rear wheel drive mode, the control unit

4B2±3 DRIVE LINE CONTROL SYSTEM (TOD)
detects the slip condition, determines the optimum torque
based on the feedback control logic, and increases the
torque to the front wheels.
The control unit uses the signal from the throttle position
sensor to predict the future vehicle condition and the
intention of the driver with respect to acceleration and
deceleration, and determines the initial torque distribution
using these data and the information from the speed
sensors.
In case of small circle turning in the parking lot, for
example, the control unit minimizes the clutch pressing
force restrict a braking phenomenon. When the ABS
becomes active, the control unit optimizes the clutch
pressing force to ensure stable braking.
TOD Indicator Control
The TOD indicator on the instrument panel informs the
driver of the current working status of the transfer unit.
The information consists of two items: the drive mode
(2H, TOD, 4L, transition) and the torque split status of the
TOD (torque distribution level). The indicator can display
occasional errors and corresponding error codes.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±4
System Components
Parts Location
A07RW020
Legend
(1) T/F Connector
(2) 4H Switch and 4L Switch
(3) High-Low Planetary Gear Set
(4) Mechanical Lock(5) Multi Plate Disk Clutch Pack
(6) Electromagnetic Coil
(7) Rear Speed Sensor
(8) Front Speed Sensor

4B2±5 DRIVE LINE CONTROL SYSTEM (TOD)
Front and Rear Speed Sensors
The sensors are built in the transfer case, detect the
rotation of rotors directly coupled to the propeller shafts.
Thirty rectangular pulses are output per one rotation of
the propeller shaft.
261RW045
Electromagnetic Coil
Receives the duty signals from the TOD control unit and
controls the pressing force of the clutch pressure cam.
261RW044
Multi Plate Disk Clutch Pack
Transmits the torque determined by the clutch pressing
force to the front propeller shaft via the front drive chain.
262RW029
Mechanical Lock Sleeve
Couples the front and rear propeller shaft mechanically
when the transfer shaft is in the 4L position.
262RW028

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±6
High-Low Planetary Gear Set
Establishes an auxiliary transmission mechanism. When
the transfer shift lever is set to the 2H or TOD position, the
reduction gear ratio is 1.000 and the corresponding
driving force is generated. When the transfer shift lever is
set to the 4L position, the reduction gear ratio is 2.480 and
the corresponding driving force is generated.
262RW030
4H and 4L Switches
Detects the shift position of the transfer from the
movement of the transfer lever and outputs signals to the
TOD control unit.
261RW002
Transfer Connector
Transmits the input and output signals of the speed
sensors, electromagnetic coil, and 4H and 4L switches to
the vehicle harness. A waterproof 12-pin type is used.
261RW046
TOD Indicator Lamps (on the instrument
panel)
Inform the following items.

Bulb check

Drive mode

ABS IN status

BRAKE ON status
821RW049

4B2±7 DRIVE LINE CONTROL SYSTEM (TOD)
Check Lamp
Inform the following items.

Bulb check

Fail (fail alarm)

Trouble code

Diesel/gasoline MAP
821RW078
TOD ECU
This control unit is mounted to the front right hand seat via
a special bracket.
F07RW029

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±8
Functions of Indicator Lamp
TOD Indicator Lamps
C07RW045
Indication During Transition of Transfer Lever
When the transfer lever is shifted, and the signals from
the AXLE switch do not comply with the signal conditions
of the 4H and 4L switch, the transfer lever position signals
generated by the 4H and 4L switch and the N position
signals are repeatedly output at an interval of 0.8 second.NOTE: After the transfer lever is set to the specified
position and the AXLE switch generates compliant
signals, the normal output status is returned.

4B2±9 DRIVE LINE CONTROL SYSTEM (TOD)
C07RW061
Bulb Check
When the starter switch is turned on, the TOD indicator
lamps go on as shown below.NOTE: Once the starter switch is turned on, all the TOD
indicator lamps are lit for two seconds even if the transfer
lever is in any position.
C07RW016