ECU ISUZU TROOPER 1998 Service Owner's Manual

4A2B±22DIFFERENTIAL (REAR 244mm)
2. Install the pinion mate gear with thrust washer by
engaging it with the side gears while turning both
pinion mate gears simultaneously in the same
direction.
425RS048
3. Install differential shaft.
1. Be sure to install the differential shaft so that it is in
alignment with the lock pin hole in the differential
cage.
425RS049
4. Install lock pin.
After lock pin installation, stake the case to secure the
lock pin.
5. Install ring gear.6. Tighten the bolts in diagonal sequence as illustrated.
Torque: 177N´m (18.0kg´m/130 lb ft)
NOTE: Discard used bolts and install new ones.
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DRIVE LINE CONTROL SYSTEM (TOD) 4B2±2
General Description
C07RW014±1
TOD (Torque on Demand) system is traction state control
system to vehicle.
Transfer Position and Drive Mode
Three drive modes can be selected through operation of
4WD switch and transfer lever.
Transfer Position
TOD SWModeDrive mode
HIGHON (NORMAL)2HRear wheel drive
OFF (PUSHED)TODElectronically controlled torque split
four wheel drive
4LON/OFF4LLow-speed mechanical lock-up four
wheel drive
The electronic control unit (ECU) judges the signals from
the transfer lever and controls the transfer drive mode
and shift-on-the-fly system status.
TOD Control
The TOD position usually drives the rear wheels, and
transmits the torque to the front wheels with the help of
electronically controlled torque split mechanism
according to running conditions encountered. The driving
force is directly transmitted to the rear wheels. This force
is split by the transfer and delivered to the front wheels.
The magnitude of the torque transmitted to the front
wheels is controlled by changing the pressing force of the
electromagnetic multi plate disk clutch built in the transfer
unit. The pressing force of the clutch is controlled bychanging the voltage to the electromagnetic coil mounted
to the rear of the clutch. When the clutch is completely
disengaged, the rear wheels are driven. When the clutch
is completely engaged, a rigid four wheel drive mode is
obtained. The torque split status is controlled
continuously between the rear wheel and four wheel drive
modes. This system includes front and rear speed
sensors, and throttle position sensor that monitors the
engine output.
The control unit receives signals sent from these sensors
and changes the pressing force of the electromagnetic
multi plate disk clutch to determine the torque distribution
on the front and rear wheels. Therefore, when the slip of
the rear wheels is increased against the current torque
level in the normal rear wheel drive mode, the control unit

4B2±7 DRIVE LINE CONTROL SYSTEM (TOD)
Check Lamp
Inform the following items.

Bulb check

Fail (fail alarm)

Trouble code

Diesel/gasoline MAP
821RW078
TOD ECU
This control unit is mounted to the front right hand seat via
a special bracket.
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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.
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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.)
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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.

4B2±23 DRIVE LINE CONTROL SYSTEM (TOD)
Checking Failed Pin
Connector Pin Assignment

ECU pin assignment
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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

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±30
Diagnostic Trouble Codes
CodeItemDiagnosisCheck flow No.
12Start codeNormalÐ
13RefShorted GND6
14Front speed sensorInput abnormality (open, sig or com)2
15RefShorted VB6
16Front speed sensorInput abnormality3
21TPSShorted or disconnected wiring, abnormality in
input7
23ECUCPU abnormality1
24Rear speed sensorInput abnormality (open, sig or com)5
25CHECK lampShorted14
26EMC (+)Shorted GND10
27Rear speed sensorInput abnormality4
28ADC (+) & AXLE SWOutput abnormality11
31EMC (+)Shorted or disconnected coil/wiring9
32ADC (+)Shorted or disconnected coil/wiring12
33ADC (+)Shorted GND13
34D-G MAPInput abnormality8
35CHECK lampShorted or disconnected wiring14
36ECUCPU abnormality1
37ECUCPU abnormality1
38ECUCPU abnormality1
TPS : Throttle Position Sensor
EMC : Electromagnetic coil
ADC : Shift on the fly (Axle Dis Connect)
D-G MAP : Discrimination engine type

4B2±31 DRIVE LINE CONTROL SYSTEM (TOD)
Diagnosis from Trouble Codes

Diagnose the TOD based on the fault that has been
saved to the control unit according to the system
self-diagnostic function.
Check flow
Trouble codePhenomenonStandard
1 23, 36, 37, 38The ECU is failed.Ð
StepActionYe sNo
1Turn on the starter switch.
Is the trouble reproduced?Replace the ECU
and conduct the
test run.
Go to Step 3
Go to Step 2
21. Clear the trouble codes.
2. Conduct the test run.
Is the trouble reproduced during the test run?
Replace the ECU
and conduct the
test run.
Go to Step 3
The trouble is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
Go to Step 3
31. Check that all the parts are mounted.
2. Clear the trouble codes.
Is this step complete?
Repeat the
ªDiagnosis Flowº.
Return to Step 3

4B2±35 DRIVE LINE CONTROL SYSTEM (TOD)
StepActionYe sNo
11. Connect TECH 2.
While running in TOD mode, does TECH±2's front speed sensor
indication change with vehicle speed?
Go to Step 2
Repair and
inspection front
speed sensor
tone wheel.
Go to Step 4
2Is the continuity harness of terminal 24 (vehicle side terminal of
the front speed sensor)?Replace speed
sensor.
Go to Step 3
Repair the circuit.
Go to Step 3
31. Clear the trouble code.
While running at 40 kph in TOD mode for 30 consecutive sec, is
trouble code reissued?
Replace ECU.
Go to Step 4
Go to Step 4
41. Check that all the parts are mounted.
2. Clear the trouble code.
Is this step complete?
Repeat the
ªDiagnosis Flowº.
The trouble is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
Return to Step 4