1998 ISUZU TROOPER check engine

4B1±11 DRIVE LINE CONTROL SYSTEM (SHIFT ON THE FLY)
Functions of Indicator Lamp
Indication of vehicle condition : Indicator lamp is
controlled by 4WD control unit and shows vehicle
conditions as below.
Indicator
Vehicle condition4WD switchTransfer position
switchFront axle switch
Off2WDOff (Close)2WD (Open)2WD (Open)
On4WDOn (Open)4WD (Close)4WD (Close)
Blink (2Hz)OperatingOn (Open)4WD (Close)2WD (Open)
Off (Close)2WD (Open)4WD (Close)
Blink (4Hz)Stop operatingOn (Open)2WD (Open)2WD (Open)
Off (Close)4WD (Close)4WD (Close)
Bulb check :To check the bulb of indicator lamp, the
indicator lamp comes on when ignition key is turned on,
and goes off when the engine is started.
Retrials from 2WD to 4WD :In cold weather or under
high speed condition, the gear shifting (engagement)sometimes does not complete by 3 trials. In such case,
the indicator lamp inform driver of this incident as
aforementioned chart (shown at Retrial in Outline of shift
on the fly system).
Diagnosis
Before Judging That Troubles Occur
(Unfaulty mode)
When Switching from 2WD to 4WD
1.In case that blinking frequency of the 4WD
indicator changes from 2Hz to 4Hz.
When heavy synchronization load is needed, the
motor actuator tries the shifting transfer gear three
times including the activation shifting. While the
motor actuator tries shifting, the indicator blinks by
2Hz. If the third shifting fails, the indicator's blinking
changes from 2Hz to 4Hz at the same time that the
motor actuator shifted back to 2WD.
Heavy synchronization load occurs by:

extremely lower temperature.

higher speed, rotation difference of wheels during
cornering.
Solution 1: Operate again after stop the vehicle or
slow down.
2.In case that the 4WD indicator continues blinking
by 2Hz for more than 11.5 seconds.
When there is rotation difference of wheels or there
is phase difference between front wheels and axles,
it is difficult to connect front wheels to front axles. The
blinking by 2Hz shows that shifting the transfer gear
or connecting the front wheels is in the middle of
operating. In above case, the indicator's blinking by
2Hz shows that connecting the front wheels is not
completed (because the indicator's blinking changes
to 4Hz when the shifting transfer gear is impossible.).
And removal of rotation or phase difference make
connecting the front wheels possible.
Solution 2: When vehicle is running, drive
straight ahead while accelerating and
decelerating. When vehicle is at a stop, move the
vehicle forward and backward from 2 to 3 meters.When switching from 4WD to 2WD
1.In case that the 4WD indicator continues blinking
by 2Hz .
The 4WD indicator continues blinking by 2Hz until
both shifting the transfer gear and disconnecting the
front wheels are completed when switching 4WD to
2WD. When driveline is loaded with torsional torque,
the shifting transfer gear and disconnecting front
wheels are impossible. In this case, removal of
torsional torque on driveline make the shifting
transfer gear and disconnecting front wheels
possible.
Solution 3: When vehicle is running, drive
straight ahead while accelerating and
decelerating. When vehicle is at a stop, move the
vehicle forward and backward from 2 to 3 meters.
2.In case that the 4WD indicator's blinking changes
from 2Hz to 4Hz.
Check the position of transfer lever. Is it at ª4Lº
position? In view of the shifting mechanism of
transfer, the gear shifting from 4WD to 2WD at ª4Lº
condition is impossible.
Solution 4: Push the 4WD switch to 4WD, shift the
transfer lever to ªHighº position and re±operate
the 4WD switch to 2WD.

4B1±25 DRIVE LINE CONTROL SYSTEM (SHIFT ON THE FLY)
Diagnosis of the Faults Based on the
Status of 4WD Indicator Lamp, 4WD
Switch and T/F Change Lever
Diagnosis charts are shown on below. If troubles can not
be solved after every chart was traced, troubles may
occur in the 4WD control unit. In this case, replace the
4WD control unit and trace every chart again.
Fault on switching from 2WD to 4WD
1.In case that 4WD indicator's blinking changes
from 2Hz to 4Hz after Solution 1 is carried out.
Faults occur in the motor actuator or the transfer case
assembly. Remove the motor actuator and check
function. If problem was found and it was repaired, try
Solution 1 again. After that, disassemble the
transfer case assembly for check and repair or
replace. If incident is not improved after above
mentioned actions were taken, replace the 4WD
control unit.
2.In case that 4WD indicator does not blink nor
light, when switching from 2WD to 4WD.
Step
ActionYe sNo
1Is ignition turned on?
Go to Step 2
Turn on the
ignition and trace
this chart from
start.
2
Does the indicator light comes on when the engine is not started?
Go to Step 3
Burning out of
indicator lamp or
disconnection of
harness wire.
Trace this chart
from the start
after repair or
replace.
3Start the engine.
Is the 4WD switch turned from 2WD to 4WD?Short-circuit
(body short) on
harness of the
4WD switch.
Fault of the 4WD
switch (holding
the closed
condition).
Trace this chart
from the start
after repair or
replace.
Push the 4WD
switch to 4WD.

4B1±33 DRIVE LINE CONTROL SYSTEM (SHIFT ON THE FLY)
Inspection and Repair
Vacuum Piping
C04RW014
1. Pull out the Hose A in figure and install a vacuum
gauge.
2. Plug up Hose B in figure to prevent the leak of
vacuum.
3. Start the engine and measure vacuum 2 or 3 minutes
afterward.
4. Repeat 1) and 2) but with Hose A plugged and Hose B
pulled out.
5. If vacuum measures ±400mmHg, or if it shows a
sudden drop immediately after engine stop, inspect
the hose, tank, and pipe for damage.
NOTE: Be careful not to permit the entry of dust and
water during inspection.
6. Pull out Hose D in above illustration.
7. Plug Hose E in above illustration.
8. Make sure that Hose D in above illustration is under
atmospheric pressure.
9. Pull out Hose E and plug Hose D, and make sure that
Hose E is under atmospheric pressure.
10. If Check 8) or 9) has revealed stoppage, check and
see that there is no bend, foreign matter in the hose or
in the filter. If there is trouble, repair or replace.Check Valve
C04RS004
1. Apply vacuum from the orange colored side(1).
Vacuum:±400mmHg
2. Check leakage of vacuum.
3. Make sure that vacuum cannot be applied from the
black colored side(2).

4B1±34
DRIVE LINE CONTROL SYSTEM (SHIFT ON THE FLY)
4. If vacuum is not applicable as much as ±400mmHg,
and if there is resistance on the intake side, replace
with a new check valve.
VSV Assembly
Inspect the vehicle side harness as follows:
412RS071
Legend
(1) Grey
(2) Blue
1. Remove connector.
2. Shift transfer lever to 2H and start the engine.
NOTE: Do not move the vehicle while inspection.
3. Make sure that there is continuity in the vehicle side of
harness. If there is no continuity, check transfer shift
switch and wiring.
Inspect both VSVs as follows:
F04RS004
1. With battery not connected (Usual).
A±C:There is continuity
B:Closed
2. With battery connected
A ± B:There is continuity
C:Closed
3. If 1) and 2) fail, replace with a new VSV.
Axle Position Switch
412RS048
1. With ball (1) being free
A ± B:There is continuity
2. With ball forced into the switch
A ± B:No continuity
3. If 1) and 2) fail, replace with a new switch.
Motor Actuator Assembly
Inspect the function of the motor actuator assembly as
follows:

4B2±11 DRIVE LINE CONTROL SYSTEM (TOD)
The CHECK lamp also has the following functions.
D-G MAP recognition and display (The control unit
displays what type of vehicle, diesel or gasoline
vehicle, it recognizes.)
1. Short-circuit the self-diagnostic connector.
2. Turn on the starter switch. (Displays with respect to
the self-diagnosis begin to appear.)
NOTE: Do not start the engine.
3. Shift the transfer lever to the neutral position between
HIGH and 4L.
4. After all the conditions in 1 through 3 above are met,
set the throttle to the WOT (wide open throttle)
position (i.e., full open position). The display of the
self-diagnosis is temporarily suspended, and the
CHECK lamp begins to display that MAP is
recognized by the TPS (throttle position sensor)
according to the current conditions.NOTE: If the TPS has failed, this function might not work.
1. When the control unit recognizes the vehicle as
gasoline type, the CHECK lamp is turned on for five
seconds and this mode is repeated at an interval of
0.3 second.
2. When the control unit recognizes the vehicle as
diesel type, the CHECK lamp is turned off for five
seconds and this mode is repeated at an interval of
0.3 seconds.
3. Upon completion of step 4, the system resumes the
self-diagnosis. (The self-diagnosis is executed
from the beginning.)
5. Turn off the starter switch once. When above
conditions are met again in the future, the TPS MAP
control can be started.
C04RW010

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±14
How to Clear The Trouble Code
The trouble codes saved to the control unit can be deleted
by the following procedure if the starter switch is being in
the OFF position.
1. Shift the transfer lever to the neutral position between
HIGH and 4L, and short-circuit the self-diagnostic
connector.
NOTE: The neutral position between HIGH and 4L refers
to the point that turns off the TOD indicator lamps.
(However, be sure to check the position before
short-circuiting the self-diagnostic connector.)
C07RW011
2. Turn on the starter switch while maintaining the state
of step 1, and step on the brake pedal five times within
five seconds from the first step on. (Note that ªfive
timesº includes the first step on). (The TOD indicator
lamps display the 4L mode whenever the brake pedal
is stepped on.)
3. If the conditions shown in steps 1 and 2 are met, clear
the trouble codes saved to the control unit. (After the
codes are completely deleted, the code 12 that
indicates the normal condition is continuously
displayed.)
Precautions on Diagnosis
Replacement of Control Unit
The control unit itself rarely fails. In most cases, the
harnesses have failed (e.q. short-circuit) to cause
secondary troubles. Other cases include that the cause
has been unknown due to intermittent occurrence of
troubles and the troubles are removed accidentally along
with replacement of control unit, resulting in misjudgment
of cause. Therefore, before replacing the control unit,
check the connector joints and whether the unspecified
current flows in the control unit due to short-circuit
between harnesses.Trouble Intermittently Observed
Troubles intermittently observed are mostly attributable
to temporary imperfect connection of harnesses and
connectors.
When such troubles are found, check the associated
circuit according to the following procedure.
1. Check whether improper connectors are plugged in
or connector terminals are completely engaged.
2. Check whether the terminals are deformed or
damaged. If yes, remove the deformation or damage
and connect the terminals securely.
3. It is likely that wires in the harness are falsely broken.
Therefore, in examination of failed harness circuit,
shake the harness for check to such extent that the
harness will not be damaged.
Test Run of Filed TOD Vehicle
If the TOD indicator lamps experienced faulty operation
even once in the past, the failed portion can be identified
by use of the procedure ªDiagnosis from Trouble Codesº
or ªTrouble Diagnosis Depending on The Status of TOD
Indicatorº. If the troubles that are only recognized as
abnormal phenomena of the vehicle by the driver are
observed, conduct the test run in the following procedure
to reproduce the faulty phenomena and diagnose the fault
for each phenomenon.
1. Start the engine, and check that the TOD indicator
lamps are turned on for about two seconds for initial
check; the CHECK lamp goes off; and the TOD
indicator lamps display the specified drive mode. (If
the CHECK lamp starts blinking, read the trouble
codes and identify the failed portion.)
2. While keeping the vehicle standstill, operate the 4WD
switch and shift the transfer lever to change the
modes: 2H mode"TOD mode"4L mode"TOD
mode"2H mode. Check that the TOD indicator
lamps correctly display the status whenever the
mode is changed. If the transition status is displayed
during the shift operation, run the vehicle a little to
complete shifting.
3. Slowly start the vehicle in the TOD mode, and add the
power to accelerate to at least 40 km/h and maintain
the speed for about two minutes. Apply the brake to
completely stop the vehicle. Repeat this test pattern
at least three times.
4. Turn the steering to the right end (or left end) in the
TOD mode, and slowly start the vehicle and make a
circle five times. Next, conduct the same test in the 2H
mode.
5. Slowly start the vehicle in the TOD mode, and
accelerate to at least 40 km/h. Keep the established
speed, carefully change the mode in the sequence
ªTOD mode"2H mode "TOD modeº while checking
that the shift is complete in each mode change. After
the test, apply the brake to completely stop the
vehicle.
6. Slowly start the vehicle in the TOD mode, and
accelerate to at least 40 km/h. Apply the brake
strongly so that the ABS works, and completely stop
the vehicle.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±24
No.NAMECONTENTS
1VIGPower supply (IG)
2N.CNot used
34WD OUT4WD signal output
4SOL (+)Electromagnetic solenoid
5ADC (+)Axle disconnect output
6LIGHTING SWLighting SW input
7BRAKEBrake SW input
84H SW4H SW input
94L SW4L SW input
10AXEL SWAXEL SW input
11ABS INOperation signal input
12TOD SWTOD SW input
13DIAGSelf-diagnosis input
14D-G MAPD-G MAP recognition input (Only V6 engine)
15Ref.Vehicle speed sensor supply
16N.CNot used
17US/JAPDestination recognition input
18COM (±)Vehicle speed sensor GND
19S-GNDSensor GND
20P-GNDPower GND
21TPSThrottle position sensor
22TECH 2TECH 2 output
23Rer. SigRear vehicle speed sensor input
24Frt. SigFront vehicle speed sensor input
25IND.a4WD disply signal a
26IND.b4WD display signal b
27IND.c4WD display signal c
28IND.AUTOAUTO display output
29IND RrRear display output
30CHECKTOD warning lamp

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±26
Checking Failed TOD Control Unit Pin
NOTE:
1. Unplug the ECU connector and the pins, unless
otherwise specified.2. Before removing the ECU, turn off the ignition switch.
3. If the standard values are not observed, check the
pins with other testers.
Check
Pin
No.Circuit to be
testedIgnition
Switch
PositionEngine
StateMultimeter
Scale/
RangeMeasure
between Pin
NumberStandard ValveNote
14D-G MAPOFFSTOP
14, 19Continuity : OK
(Gasoline)
20P-GNDOFFSTOP
20, 19Continuity : OK
19GNDOFFSTOP
19, GNDContinuity : OK
84H SWOFFSTOP
8, 19No continuity (high,
4L) and continuity
(N) : OK
94L SWOFFSTOP
9, 19No continuity (high)
and continuity (4L,
N) : OK
10AXLE SWONRUN
10, 19Continuity : OKRemove ECU and start the engine. Move
the vehicle forth and back to connect axle
surely.
13DIAGOFFSTOP
13 (TOD), 8
(DLC Con-
nector)Continuity : OKDLC connector terminal 8
25IND.aONSTOPDCV25 (+), 19 (±)8.0 ~14.5 VLighting SW ON : 0V
Lighting SW OFF : 8.0 ~14.5 V
26IND.bONSTOPDCV26 (+), 19 (±)8.0 ~14.5 V
27IND.cONSTOPDCV27 (+), 19 (±)8.0 ~14.5 V
30CHECK
LAMPONSTOPDCV30 (+), 19 (±)8.0 ~14.5 V
11ABS INONSTOPDCV11 (+), 19 (±)11.5 ~14.5 V
15Ref.ONSTOPDCV15 (+), 19 (±)5 ~9 VConnect ECU
24Ft.(+)ONSTOPDCV24 (+), 19 (±)0.7 ~6 VConnect ECU (off one tooth of speed
sensor ring) and move the vehicle making
sure of voltage change.
23Rr.(+)ONSTOPDCV23 (+), 19 (±)0.7 ~6 VConnect ECU (off one tooth of speed
sensor ring) and move the vehicle making
sure of voltage change.
18COM(-)ONSTOPDCV18 (+), 19 (±)0VConnect ECU
1VigONSTOPDCV1 (+), 19 (±)8 ~14.5 V
7BRAKEOFFSTOPDCV7 (+), 19 (±)8 ~14.5 VPress brake pedal
21TPSONSTOPDCV21 (+), 19 (±)0.2 ~4.6 VStep on the accelerator pedal and make
sure that voltage changes.
34WD OUTOFFSTOP
3, 197 ~12 k
Disconnect battery GND terminal
5ADC(+)OFFSTOP
5, 1910 ~30
Disconnect battery GND terminal
4SOL(+)OFFSTOP
4, 191.0 ~5.0
Disconnect battery GND terminal
12TOD SWONSTOPDCV12 (+), 19 (±)SW OFF : 0 V
SW ON : 8.0 ~14.5 VSW OFF : Contact point open
SW ON : Contact point close
6LIGHTINGONSTOPDCV6 (+), 19 (±)SW OFF : 8.0 ~14.5
V
SW ON : 0 V
28AUTO INDIONSTOPDCV28 (+), 19 (±)TOD : 0 V
2H & 4L : 8.0 ~14.5
VLighting SW ON : 0V
Lighting SW OFF : 8.0 ~14.5 V
29RR INDIONSTOPDCV29 (+), 19 (±)0 V
17US/JAPOFFSTOP
17 (+), 19 (±)No continuity : OK