2002 ISUZU AXIOM Service Repair Manual

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±6
High-Low Planetary Gear Set
Establishes an auxiliary transmission mechanism. When
the TOD switch is set to the 2H or TOD position, the
reduction gear ratio is 1.000 and the corresponding
driving force is generated. When the TOD switch is set to
the 4L position, the reduction gear ratio is 2.480 and the
corresponding driving force is generated.
262RW030
4H and 4L Switch
Detects the shift position of the transfer from the
movement of the shift rod and outputs signals to the TOD
control unit.
261RW002
Transfer Connector (12-pin type)
Transmits the input and output signals of the speed
sensors, electromagnetic coil, and 4H and 4L switche to
the vehicle harness. A waterproof 12-pin type is used.
261RW046
Transfer Connector (8-pin type)
Transmits the output signals of the shift motor position to
the vehicle harness and power for the shift motor to the
transfer. A waterproof 8-pin type is used.
261RY00039

4B2±7
DRIVE LINE CONTROL SYSTEM (TOD)
TOD Indicator Lamps (on the instrument
panel)
Inform the following items.

Bulb check

Drive mode

ABS IN status

BRAKE ON status
821R200016
Check Lamp
Inform the following items.

Bulb check

Fail (fail alarm)

Trouble code
821R200016

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±8
TOD ECU
This control unit is mounted to the clutch pedal position
via a special bracket.
826R200019
Legend
(1) Brake Pedal Bracket

4B2±9
DRIVE LINE CONTROL SYSTEM (TOD)
High-Low Shift Motor
F07R200002
Legend
(1) Reduction Hub
(2) Mechanical Lock Sleeve (Including the built-in
Spring)
(3) Lockup Shift Fork
(4) Return Spring
(5) To TOD Control Unit
(6) Fixed Contact Point
(7) Encoder
(8) Worm gear
(9) Rotate
(10) Shift Motor
(11) The shift cam (12) can be turned freely around
the shift shaft (14).(12) Shift Cam
(13) Torsional Spring
(14) Shift Shaft
(15) Shift Rod
(16) High-Low Shift Fork
(17) High
(18) Low
(19) 2H and TOD Position
(20) Direct Four Wheel Drive (4L Position)
(21) Earth
(22) High
(23) Low
(24) High
(25) Low
When the TOD switch is changed to the 4L (or TOD)
position from the TOD (or 4L) position, the TOD control
unit drives the high±low shift motor according to the
signal. The transfer is shifted to low range from high range
(or to high range from low range) by the shift motor.
The high-low shift motor can run, only when the operation
meets the following conditions to prevent an unexpected
shift between high and low range by a operation error.
1. The car stops. (less than 2 km/h or 1.2 mph and less
than 1500 rpm.)2. The AT selector position is neutral.
3. The brake is applied. (brake switch is on.)
The shift motor has a built-in encoder which watches
motor rotation position. The control unit controls the
rotation of the shift motor based on the position code
detected by the encoder.
The encoder position plate turns together with the shift
shaft and switches on or off the current from the 4 (four)
fixed contact points on the case, then the control unit
recognizes the rotation position of the shift motor.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±10
Motor Position and Encoder Position Code
High-Low Shift Motor PositionHigh-Low shift Motor Encoder SignalState of
MotorPosition aPosition bPosition cPosition dMotor
High EndAOFFOFFOFFONHigh Position
Near High EndBOFFONOFFON
High PositionCONONOFFON
Middle Zone (1)DONONONON
Middle Zone (2)EOFFONONON
Neutral PositionFOFFONONOFF
Middle Zone (3)GONONONOFF
Low PositionHONOFFONOFFLow Position
Low EndIONOFFONON
Encode Position Plate
F04R100005
Legend
(1) OFF Aria
(2) ON Aria(3) Low
(4) High
(5) Earth
Shift High Range and Low Range
When the car is stops (less than 2km/h or 1.2 mph and
less than 1500 rpm), the AT selector position is neutral,
the brake is applied, and the TOD switch is changed to 4L
from TOD (or to TOD from 4L), the high-low shift motor
starts by power applied from the TOD control unit and
turns the shift shaft through the worm gear.
The shift shaft turns the shift cam through the torsional
spring.
The end of the shift cam moves the lockup shift fork and
the spiral groove on the outside of the shift cam slides the
high±low shift fork.

4B2±11
DRIVE LINE CONTROL SYSTEM (TOD)
Functions of TOD Switch and
Indicator Lamp
TOD Switch and Indication of Drive Mode
The TOD switch sends signals to the TOD control unit
which selects drive modes and controls the shift on the fly
system (axle disconnect : ADC).
TOD
switch
state
Drive modeTransfer shift conditionTransfer
position
detectionShift on the flyTOD indicator
state
4HSW4LSWAxle
SWADC circuit
2HRear-wheel
drive (RWD)Permissible during
driving (less than
100 km/h or 62 mph)OFFOFFOFFTurning on
electricity
TODElectronic
torque split
4WD (TOD)OFFOFFONTurning off
electricity
AT: Neutral
Brake: Applied
The car stops4LLow range
mechanical
direct 4WD
(4L)The car sto s
(less than 2 km/h or
1.2 mph and less than
1500 rpm)OFFONONTurning off
electricity
ADC: Shift on the fly
SW: Switch
TOD
Switch
TOD control unit terminal No.TOD indicator
stateSwitch
stateTOD indicatorTOD switchstate
state
7(Front)8(Rear)19(Auto)30(2H)43(4L)
2HOFFONOFFONOFF
TODONONONOFFOFF
4LONONOFFOFFON

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±12
Indication During Transition of Shift Rod
When the TOD switch is turned, and the signals from the
AXLE switch do not comply with the signal conditions of
the 4H and 4L switch, the indicator lamp state selected on
the TOD switch and light-off mode are repeatedly output
at an interval of 1.0 second.NOTE: After the TOD switch is turned to the specified
position and the AXLE switch generates compliant
signals, the normal output status is returned.
C07R100010
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 TOD
switch is in any position.
C07RW016

4B2±13
DRIVE LINE CONTROL SYSTEM (TOD)
Simplified checking method of ABS IN and BRAKE ON signals:
In the event that any of the signal inputs listed below are
observed while the self-diagnostic code is being
displayed (the self-diagnostic connector is short-circuited
to GND), you can simply check the ABS IN and BRAKE
ON signals as shown in the figures below.
C07R200002
Check Lamp
Check Lamp Bulb Check
When the starter switch is turned on in the normal state,
the control unit turns on the CHECK lamp to check the
bulb.
C07RW019