Isuzu KB P190. Manual — part 1233

7D1-58 TRANSFER CONTROL SYSTEM

Transfer cannot shift to another position (Except “Check 4WD” failure).

When shifting to another position, indicator (4WD, 4Lo, Check4WD, neutral) does not
respond (Current condition keeping).

Step Action

Yes

No

1

Is the ignition switch ON?

Go to step 2.

Failed indicator and harness
(When lighting).
After repairing, trace this chart
from the beginning.

2

Does the transfer-related
indicators (4WD, 4Lo, Check
4WD, neutral) light up for 2
seconds when the ignition switch
is turned ON?

Go to step 3.

All indicators are burnt out
(Check for GND short circuit
between the indicator and
transfer controller).
Disconnected harness wire.
After repairing, trace this chart
from the beginning.

3

Press the other positions button.
Is the sound of relay heard from
under the seat, and the sound of
a running motor heard?

Failed controller.
After replacing the controller,
trace this chart from the
beginning.

*Failed operation switch. Or
harness for the operation switch
has disconnected or shorted.

* The operation switch is an analog type switch which reads the internal composite resistance value at the time of

operation. If an abnormal value is detected, it is kept at the home position (The position before operating it).

TRANSFER CONTROL SYSTEM 7D1-59

Even after the correction step 2-1(*), the 4WD indicator still blinks at 2Hz when shifting
from 4H to 2H.

Step Action

Yes

No

1

Check all the tires for air
pressure and wear. Is any
trouble detected?

After adjusting the air pressure
and repairing the worn tires, try
the correction step 2-1(*).

Go to step 2.

2

Check the 4WD detection switch
on the transfer case and neutral
detection switch and each
harness. Is a trouble detected?

4WD detection switch is closed
or the GND short of harness.
The neutral detection switch is
closed or the harness GND has
shorted.
Replace or repair and then trace
this chart from the beginning.

Go to step 3.

3

Is there continuity in the harness
between the transfer controller
and axle actuator?
Has a short or disconnection
been detected?
Is the connection incorrect?

Go to step 4.

Body short, disconnection or
incorrect connection of the
harness between the transfer
controller and actuator.
After repairing, trace this chart
from the beginning.

4

Is trouble detected in the axle
detection harness between the
axle actuator and transfer
controller?

GND short of harness

Malfunction of axle actuator.
Refer to the paragraph of axle
disconnect.
After repairing, trace this chart
from the beginning.

*Before determining a trouble (Non-trouble mode)

Note:
Vehicle with manual hub and rigid hub don’t have axle actuator.
When the above-mentioned procedure is followed, check the harness between the axle dummy output terminal and
the axle switch input terminal of the transfer controller, instead of axle actuator.

7D1-60 TRANSFER CONTROL SYSTEM

Though the indicator responds when shifting from 4H to 2H(or other position), it returns
to 4H.

Step Action

Yes

No

1

Is the ignition switch ON?

Go to step 2.

Turn the ignition switch ON and
trace this chart from the
beginning.

2

Does the transfer-related
indicators (4WD, 4Lo, Check
4WD, neutral) light up for 2
seconds when the ignition switch
is turned ON?

Go to step 3.

Indicator lamp burnt out.
Disconnected harness wire.
After repairing, trace this chart
from the beginning.

3

After 2 seconds, check if the
Check4WD lamp lights up.
Is the Check4WD lamp OFF?

Go to step 4.

Failed actuator position detection
(limit) switch (LS1, LS2, LS3,
LS4, GND).
Short or disconnection of harness
of this detection switch.
Refer to paragraph of
Check4WD.
After repairing, trace this chart
from the beginning.

4

Press the 2H button.
Is the sound of relay heard from
the transfer controller?

Go to step 5.

Failed controller.
Replace the controller and trace
this chart from the beginning.

5

Is the sound of a running motor
heart?

Failed control system of the
transfer mechanism. Check and
repair and trace this chart from
the beginning.

Failed actuator motor.
Disconnection of controller motor
drive output circuit or GND short.
After repairing, trace this chart
from the beginning.

If the motor does not or cannot run at all (stuck transfer mechanism, disconnected motor, failed drive circuit), the
lamp blinks at 4Hz when the position is shifted to other position by pressing the button for more 10 seconds (20
seconds in case of neutral position).

TRANSFER CONTROL SYSTEM 7D1-61

From 4H to 4L; Even after the correction step 3-3(*), 4Lo indicator blinks at 4Hz

Step Action

Yes

No

1

Is the ignition switch ON?

Turn it OFF once.

Go to step 2.

2

Turn ON the ignition switch and
check the valve. Do not start
the engine.
Has the valve check for 2
seconds been completed
normally?

Go to step 3.

Refer to the paragraph about the
indicator when it does not react
when shifted from 2H to 4H.
After taking the remedy, trace this
chart from the beginning.

3

Shift to 2H.
Can be shifted to 2H and then to
4H?

Go to step 4.

Refer to the paragraph about
shifting from 2H to 4H.
In particular, check if not at the
Check4WD condition, return to
this chart and trace it from the
beginning.

4

Set to N position in case of AT
and set to the neutral position in
case of MT and check if the
lamp blinks at 4Hz after
operation.

Failed T/M position switch and
harness (failure of TM1 and TM2
harness and their related
switches shown in the figure).
Incorrect wiring.
Repair as required and trace this
chart from the beginning.

Shift back to 4H and go to step 5.

5

Start the engine and use the
vehicle.
Does the speedometer run at
this time?

Go to step 6.

Failure of speed sensor or
disconnection or short of harness
(for the meter).
After repairing, trace this chart
from the beginning.

6

Check the harness between the
transfer controller and speed
sensor.
(Check the engine rotation
detection harness at the same
time.)
Is any trouble detected?

Failed harness between the
transfer controller and speed
sensor.
After repairing, trace this chart
from the beginning.
(Repair the engine rotation
detection unit, if required.)

Go to step 7.

7

Run the vehicle for several
meters, stop it, meet the
permission requirements for
operation limits.
Did you wait for several seconds
after the requirements were
met?

Failed controller.
Replace the controller and trace
this chart from the beginning.

You did not wait for enough time.
Optimum waiting time is 1 second
or maximum 3 minutes,
depending on the previous
conditions.
Refer to the paragraph about
operation without failure.

*Before determining a trouble (Non-trouble mode)