2007 ISUZU KB P190 Neutral switch

7D1-54 TRANSFER CONTROL SYSTEM
Diagnosis from symptom
Check4WD lighting up
Step Action Yes No
1 Check what was done before the
trouble occurred.
W as the harness between the
transfer controller and actuator
disconnected with the ignition
kept ON for the purpose of
servicing the vehicle?
Or, was the ignition turned ON
(power supplied to the transfer
controller) with the harness of
the actuator removed? If the power is supplied with the
actuator not connected, a faulty
position detection switch is
considered.
Clear the memory and trace this
chart from the beginning. Go to step 2.
2
Is the ignition switch ON? Go to step 3.
Turn the ignition switch ON and
trace this chart from the
beginning.
3 Does the transfer-related
indicators (4W D, 4Lo, Check
4W D, neutral) light up for 2
seconds when the ignition switch
is turned ON? Go to step 4.
Indicator lamp burnt out.
Disconnected harness wire.
After repairing, trace this chart
from the beginning.
4 Has the harness between the
Check4W D indicator and
transfer controller GND shorted? GND (body) short of the indicator
harness.
After repairing, trace this chart
from the beginning. Go to step 5.
5
Check the continuity of harness
between the transfer controller
and transfer actuator. Check
the power short and GND short.
Check the GND harness of the
transfer actuator.
Is a trouble noticed? Repair the harness, clear the
memory and trace this chart from
the beginning. Go to step 6.
6
Check the limit switch of the
actuator.
Is a trouble noticed? Failed actuator. Replace the
actuator, clear the memory and
trace this chart from the
beginning. Clear the memory and trace this
chart from the beginning.
Failed controller.
Replace the controller, clear the
memory and trace this chart from
the beginning.
To check the operation after completing the repair and clearing the memory, shift between 2H and 4L at least 5
times.
To judge the condition more quickly, ask the customer what happens when the Check4W D lamp lights up.
W hen the position indicator blinks at a frequency of 4Hz immediately after trouble occurs, the position of failure
which the indicator shows may be limited.
(Since it indicates the situation immediately before detection of failure, whether the vehicle is running or at a
standstill, the possibility of failure around that point is high.)
Status of the transfer when the Check4W D lights up is not always the same. Immediately after failure occurs, 2H
can be operated.



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ISUZU KB P190 2007

TRANSFER CONTROL SYSTEM 7D1-55
Cannot shift from 2WD to 4H or 4L.
When shifting from 2H to other position, the indicator (4WD, 4Lo, Check4WD, neutral)
does not respond.
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 (4W D, 4Lo, Check
4W D, neutral) light up for 2
seconds when the ignition switch
is turned ON? Failed operation switch. Or,
Failed controller. Indicator lamp burnt out.
Disconnected harness wire.
After repairing, trace this chart
from the beginning.


Even after correction step 1-1(*), 4WD indicator blinks at 4Hz and changes to 2H after 10
seconds.
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 (4W D, 4Lo, Check
4W D, 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 that the
Check4W D lamp is ON or OFF.
Is the Check4W D lamp OFF? Go to step 4.
Failed actuator position detection
switch (LS1, LS2, LS3, LS4,
GND).
Short or disconnection of harness
of this detection switch.
After repairing, trace this chart
from the beginning.
4 Press the 4H button.
Is sound of relay heard from the
transfer control? Go to step 5.
Failed controller.
Replace the controller and trace
this chart from the beginning.
5 Is the sound of a running motor
heard? Failed control system of the
transfer mechanism. Check and
repair and trace this chart from
the beginning. Failed actuator motor.
Disconnected controller motor
drive output circuit, GND short
circuit. +B fuse blown out.
Disconnection of that harness.
After repairing, trace this chart
from the beginning.
*Before determining a trouble (Non-trouble mode)




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ISUZU KB P190 2007

7D1-56 TRANSFER CONTROL SYSTEM
Even after the correction step 1-2(*), the 4WD indicator still blinks at 2Hz when shifting
from 2H to 4H.
Step Action Yes No
1 Check the air pressure and wear
of all the tires. Is any trouble
noticed? After adjusting the air pressure
and repairing the worn tires, try
the correction step 1-2(*). Go to step 2.
2
Check the 4W D detection switch
on the transfer case, neutral
detection switch and each
harness. Is a trouble noticed? 4W D detection switch is open or
the harness failed.
The neutral detection switch is
closed or the harness GND is
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 front axle actuator? Has a
body short or disconnection
been detected? Go to step 4.
Body short or disconnection of
the harness between the transfer
controller and front axle 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? Disconnected harness.
After repairing trace this chart
from the beginning. Malfunction of axle actuator.
Refer to the paragraph of the axle
disconnect.
After repairing, trace this chart
from the beginning.
*Before determining a trouble (Non-trouble mode)
Note:
Vehicles with manual hub and rigid hub don’t have axle actuator.
W hen 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.


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ISUZU KB P190 2007

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
(W hen lighting).
After repairing, trace this chart
from the beginning.
2 Does the transfer-related
indicators (4W D, 4Lo, Check
4W D, 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).



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ISUZU KB P190 2007

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 4W D detection switch
on the transfer case and neutral
detection switch and each
harness. Is a trouble detected? 4W D 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.
W hen 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.

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ISUZU KB P190 2007

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 (4W D, 4Lo, Check
4W D, 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
Check4W D lamp lights up.
Is the Check4W D 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
Check4W D.
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).



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ISUZU KB P190 2007

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
Check4W D 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)


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ISUZU KB P190 2007

7D1-62 TRANSFER CONTROL SYSTEM
From 4L to 4H: After the correction step 4-3(*), 4Lo indicator blinks at 4H.
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 Can be shifted to 2H and then to
4L? Go to step 4.
(Impossible usually.)
Failed controller In case of Check 4W D, shifting to
2H is possible.
Returning to 4L is impossible.
Refer to the paragraph about
Check4W D.
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. Press the operation switch of 4L
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 transfer 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)



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ISUZU KB P190 2007