2004 ISUZU TF SERIES light

TRANSFER CONTROL SYSTEM 7D1-17
Skip operation limitations (4L




2H) (Vehicle speed, engine speed, and transmission position not
specified)

Item 4WD
lamp 4L lampNeutral
lamp Check
4WD
warning
light 4WD
switch Actuator
detection
(limit)
switches
LS1, LS2,
LS3. and
LS4
1 = on
2 = off Transfer
4WD
switch Transfer
neutral
switch SOF
actuator
switch
Or
Axle
dummyRemarks
4L Off On Off Off Open 1,1,0,1 Closed Open Closed -----
4L start of
operation Off On Off Off 2H
position
for 0.1
second 1,1,0,1 Closed Open Closed -----
10
second
display
during
limitation Blinking
(4HZ) Off Off Off Open 1,1,0,1 Closed Open Closed No
operation
during
limitation
Go to 4L
after 10
seconds
Off ON Off Off Open 1,1,0,1 Closed Open Closed -----

Skip operation limitations (2H




4L) (Vehicle speed, engine speed, and transmission position not
specified)

Item 4WD
lamp 4L lampNeutral
lamp Check
4WD
warning
light 4WD
switch Actuator
detection
(limit)
switches
LS1, LS2,
LS3. and
LS4
1 = on
2 = off Transfer
4WD
switch Transfer
neutral
switch SOF
actuator
switch
Or
Axle
dummyRemarks
2HL Off Off Off Off Open 1,0,1,0 Open Open Open -----
4L start of
operation Off Off Off Off 2H
position
for 0.1
second 1,0,1,0 Open Open Open -----
10
second
display
during
limitation Blinking
(4HZ) Blinking
(4HZ) Off Off Open 1,0,1,0 Open Open Open No
operation
during
limitation
Go to 2H
after 10
seconds
Off Off Off Off Open 1,0,1,0 Open Open Open -----


Under some conditions, a secondary operational indication may be received when the 4Hz operational
indication is present.

7D1-18 TRANSFER CONTROL SYSTEM
Transfer-related indicator lamp and switch function
2H
Neutral
2H
Item 4WD
lamp 4L lampNeutral
lamp Check
4WD
warning
light 4WD
switch Actuator
detectio
n (limit)
switches
LS1,
LS2,
LS3. and
LS4
1 = on
2 = off Transfer
4WD
switch Transfer
neutral
switch SOF
actuator
switch
Or
Axle
dummy Remarks
2H Off Off Off Off No
operation1,0,1,0 Open Open Open -----
Neutral
start of
operation Off Off Off Off Neutral
position
for 10
seconds1,0,1,0 Open Open Open Switch
operation
sensor
Start of
operation Off Off Blinking
(2HZ) Off No
operation1,1,1,0
0,0,1,0
0,1,1,0
0,1,1,1 Open Open Open 2H to 4H
while
driving
During
operation
(Synchro) Off Off Blinking
(2HZ) Off No
operation1,1,1,0
0,0,1,0
0,1,1,0
0,1,1,1 Open Open Open 2H to 4H
using
synchro
and retrial
During
operation
(Passing
through
4H) Off Off Blinking
(2HZ) Off No
operation0,0,1,1 Closed Open Closed -----
During
operation
(Passing
through
4H) Off Off Blinking
(2HZ) Off No
operation0,0,0,1
0,1,0,1 Closed Open Closed 4H to 4L
while
driving
During
operation
(N)
Off Off Blinking
(2HZ) Off No
operation
0,0,0,1
0,1,0,1 Closed Closed Closed
4H to 4L
through
neutral
During
operation
(N) Off Off Blinking
(2HZ) Off No
operation0,1,0,0 Closed Closed Closed Switch
operation
sensor
Neutral Off Off On Off No
operation0,1,0,0 Closed Closed Open -----
2H start of
operation Off Off On Off 2H
position
for 10
seconds0,1,0,0 Closed Open Closed Switch
operation
sensor
During
operation
(Passing
through
N) Off Blinking
(2HZ) Off Off No
operation0,1,0,0 Closed Closed Closed 4L to 4H
through
neutral
During
operation Off Blinking
(2HZ) Off Off No
operation0,1,0,1
0,0,0,1 Closed Closed Closed 4L to 4H
while
driving

TRANSFER CONTROL SYSTEM 7D1-19
Item 4WD
lamp 4L lampNeutral
lamp Check
4WD
warning
light 4WD
switch Actuator
detectio
n (limit)
switches
LS1,
LS2,
LS3. and
LS4
1 = on
2 = off Transfer
4WD
switch Transfer
neutral
switch SOF
actuator
switch
Or
Axle
dummy Remarks
During
operation
(4H
waiting) Off Blinking
(2HZ) Off Off No
operation0,0,1,1 Closed Closed Closed 4L to 4H
while
waiting
During
operation
(Axle) Blinking
(2HZ) Off Off Off No
operation0,1,1,1
0,1,1,0
0,0,1,0
1,1,1,0 Closed Open Closed 2H to 4H
while
driving
During
operation
(Axle) Blinking
(2HZ) Off Off Off No
operation0,1,1,1
0,1,1,0
0,0,1,0
1,1,1,0 Open Open Closed Axle
driving
Axle
waiting
Blinking
(2HZ) Off Off Off No
operation1,0,1,0 Open Open Closed -----
2H Off Off Off Off No
operation1,0,1,0 Open Open Open -----


Operational restrictions (vehicle speed, engine speed, and transmission position) are applicable to transfer
shifts in both directions (H
Neutral
L).

7D1-20 TRANSFER CONTROL SYSTEM
4H




Neutral




4H
Item 4WD
lamp 4L lampNeutral
lamp Check
4WD
warning
light 4WD
switch Actuator
detection
(limit)
switches
LS1, LS2,
LS3. and
LS4
1 = on
2 = off Transfer
4WD
switch Transfer
neutral
switch SOF
actuator
switch
Or
Axle
dummyRemarks
4H On Off Off Off No
operation0,0,1,1 Closed Open Closed -----
Neutral
start of
operation On On Off Off Neutral
position
for 10
seconds 1,1,0,1 Closed Open Closed -----
Start of
operation Off Off Blinking
(2HZ) Off No
operation1,1,0,0 Closed Open Closed 4L to N
while
driving
During
operation
(N) Off Off Blinking
(2HZ) Off No
operation1,1,0,0 Closed Closed Closed 4L to N
with axle
driving
During
operation
(N) Off Off Blinking
(2HZ) Off No
operation0,1,0,0 Closed Closed Closed 4L to 4N
with axle
removed
During
operation
(Axle) Blinking
(2HZ) Off Off Off No
operation0,1,1,1
0,1,1,0
0,0,1,0
1,1,1,0 Open Open Closed Axle
driving
Axle
waiting
Blinking
(2HZ) Off Off Off No
operation1,0,1,0 Open Open Closed -----
Neutral Off Off On Off No
operation0,1,0,0 Closed Closed Open -----
4H start
of
operation Off Off Off Off 2H
position
for 10
seconds 0,1,0,0 Open Open Open Switch
operation
sensor
During
operation
(N) Off Blinking
(2HZ) Off Off No
operation1,1,0,0 Closed Closed Open 4L to 4H
through
neutral
During
operation
(N) Off Blinking
(2HZ) Off Off No
operation0,1,0,0 Closed Closed Open 4L to 4H
through
neutral
During
operation Off Blinking
(2HZ) Off Off No
operation0,1,0,1
0,0,0,1 Closed Closed Open 4L to 4H
while
driving
4H
waiting Blinking
(2HZ) Off) Off Off No
operation0,0,1,1 Closed Closed Open 4L to 4H
while
waiting
During
operation
(Axle) Blinking
(2HZ) Off Off Off No
operation0,0,1,1 Closed Open Open Axle
driving
Axle
waiting
Blinking
(2HZ) Off Off Off No
operation0,0,1,1 Closed Open Open -----
4H On Off Off Off No
operation0,0,1,1 Closed Open Closed -----

7D1-22 TRANSFER CONTROL SYSTEM
4L




Neutral




4L

Item 4WD
lamp 4L lampNeutral
lamp Check
4WD
warning
light 4WD
switch Actuator
detection
(limit)
switches
LS1, LS2,
LS3. and
LS4
1 = on
2 = off Transfer
4WD
switch Transfer
neutral
switch SOF
actuator
switch
Or
Axle
dummyRemarks
4L On On Off Off No
operation1,1,0,1 Closed Open Closed -----
Neutral
start of
operation On On Off Off Neutral
position
for 10
seconds 1,1,0,1 Closed Open Closed -----
Start of
operation Off Off Blinking
(2HZ) Off No
operation1,1,0,0 Closed Open Closed 4L to N
while
driving
During
operation
(N) Off Off Blinking
(2HZ) Off No
operation1,1,0,0 Closed Closed Closed 4L to N
with axle
driving
During
operation
(N) Off Off Blinking
(2HZ) Off No
operation0,1,0,0 Closed Closed Closed 4L to 4N
with axle
removed
During
operation
(Axle) Blinking
(2HZ) Off Off Off No
operation0,1,0,0 Closed Closed Closed Axle
driving
Axle
waiting
Blinking
(2HZ) Off Off Off No
operation0,1,0,0 Closed Closed Closed -----
Neutral Off Off On Off No
operation0,1,0,0 Closed Closed Open -----
4L start of
operation Off Off On Off 4L
position
for 10
seconds 0,1,0,0 Open Open Open Switch
operation
sensor
During
operation
(N) Off Blinking
(2HZ) Off Off No
operation1,1,0,0 Closed Closed Open 4H to 4L
through
neutral
During
operation
(N) Off Blinking
(2HZ) Off Off No
operation1,1,0,0 Closed Closed Open 4H to 4L
through
neutral
During
operation
(N) Off Blinking
(2HZ) Off Off No
operation1,1,0,0 Closed Closed Open 4H to 4L
through
neutral
4H
waiting On Blinking
(2HZ) Off Off No
operation1,1,0,1 Closed Closed Open 4L while
waiting
During
operation
(Axle) Blinking
(2HZ) Off Off Off No
operation1,1,0,1 Closed Open Open Axle
driving
Axle
waiting
Blinking
(2HZ) Off Off Off No
operation1,1,0,1 Closed Open Open -----
4H On On Off Off No
operation1,1,0,1 Closed Open Closed -----

Operational restrictions (vehicle speed, engine speed, and transmission position) are applicable to transfer
shifts in both directions (H
Neutral
L).

TRANSFER CONTROL SYSTEM 7D1-39
Trouble diagnosis based on the operation switch, transfer indicator lamp and operating
sound “Check 4WD” indicator ON (operation guard based on the transfer actuator
position detection error)
This condition indicates a faulty circuit related with the detection (limit) switches of the system actuator.
Detection (limit) switches detect the actuator operating angle based on their combinations.
The controller monitors transition of the actuator based on the combination of the detection (limit) switch output.
If the transition based on the combinations indicates some trouble, it is memorized, shifting operation is stopped
when the trouble is counted 5 times, and the “Check 4WD” indicator lights up. At this time, the system permits
operation to 2H only.
When such a condition results, inspection of the transfer shift actuator, check of harness related with the
detection (limit) switch, and erasure of the memory of the controller are required.
(Refer to the memory erasure procedure for the erasure of the memory.)
At this time, the position indicator may flash at 4Hz. It means that a detection (limit) switch trouble wad
detected in the operation process shown by that position indicator (example: 4WD indicator when shifting from
2H to 4H).

Caution:
In the course of trouble diagnosis and correction, do not turn ON the ignition with the harness connector of
the transfer actuator disconnected. (Do not disconnect the harness connector of the transfer actuator
when the ignition is ON.)
If the controller is connected at this condition, a limit SW trouble is judged and the above-described
“Check 4WD” condition is brought about.
This can be reset by clearing the memory.
When it is required to disconnect the harness connector of the actuator and turning the ignition ON,
remove the controller at the same time or remove the IG power fuse of the transfer controller.

TRANSFER CONTROL SYSTEM 7D1-41
Diagnosis from symptom
Check4WD lighting up
Step Action Yes No
1 Check what was done before
the trouble occurred.
Was the harness between the
transfer controller and actuator
disconnected with the ignition
kept ON for the purpose of
servicing the vehicle, etc.?
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, 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 (4WD, 4Lo, Check
4WD, 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 Isn’t the harness between the
Check4WD 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 5 times at
least.
To judge the condition more quickly, ask the customer the situation when the Check4WD lamp lighted up.
When the position indicator blinks at a frequency of 4Hz immediately after occurrence of a trouble, 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 standstill so
that possibility of failure around that point is high.)
Status of the transfer when the Check4WD lights up is not always the same. Immediately after occurrence of the
failure, 2H can be operated.

7D1-42 TRANSFER CONTROL SYSTEM
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 (4WD, 4Lo, Check
4WD, neutral) light up for 2
seconds when the ignition
switch is turned ON? Failed operation switch. Only 2H
is stuck at ON condition and 4H-
4L position is internally
disconnected. 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 (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 that the
Check4WD lamp is ON or OFF.
Is the Check4WD 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 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)