2002 ISUZU AXIOM ABS

4B2±13
DRIVE LINE CONTROL SYSTEM (TOD)
Simplified checking method of ABS IN and BRAKE ON signals:
In the event that any of the signal inputs listed below are
observed while the self-diagnostic code is being
displayed (the self-diagnostic connector is short-circuited
to GND), you can simply check the ABS IN and BRAKE
ON signals as shown in the figures below.
C07R200002
Check Lamp
Check Lamp Bulb Check
When the starter switch is turned on in the normal state,
the control unit turns on the CHECK lamp to check the
bulb.
C07RW019

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±16
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. Short-circuit terminal 8 of the self-diagnostic
connector to GND (terminal 4 or 5).
2. Turn on the starter switch while maintaining the state
of step1, and stop short-circuiting terminal 8 to GND
within five seconds.
826R200011
3. If the conditions shown in steps 1 and 2 are met, the
trouble codes saved to the control unit are cleared.
(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 (i.e. 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 Failed 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 TOD
switch 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 (25 mph)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 (25 mph). 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 (25 mph). Apply the
brake strongly so that the ABS works, and completely
stop the vehicle.
7. Slowly start the vehicle in the 4L mode, and
accelerate to at least 20 km/h (13 mph). Apply the
brake to completely stop the vehicle.
If the CHECK lamp starts blinking during the test run, read
the trouble codes and give appropriate maintenance
according to the diagnostic procedure. If the TOD
indicator lamps are lit abnormally during the run, check
the lighting condition and give appropriate maintenance
according to the diagnostic procedure. Even if the
phenomena are not observed, try to reproduce the
abnormal state reported by the customer to the possible
extent.

4B2±27
DRIVE LINE CONTROL SYSTEM (TOD)
No. CONTENTSNAME
26MTR POS1Shift Motor Position 1
27POSCAT Position C
28POSAAT Position A
29DIAGDiagnostic Input
30TOD SW ATOD Switch A (2H)
314H SW4H Switch Input
32FT. SIGFront Speed Signal
33ABS INABS In
34VBPower Bat
35MTR H-LPower Shift Motor H-L
364WD OUT4WD Signal Output
37BRAKE SWBrake Switch Input
38MTR POS4Shift Motor Position 4
39MTR POS2Shift Motor Position 2
40LIGHTING SWLighting Switch Input
41POSBAT Position B
42AXLE SWAxle Switch Input
43TOD SWBTOD Switch B (4L)
444L SW4L Switch Input
45RR. SIGRear Speed Signal
46GND. 1ECU Ground 1
47GND. 2ECU Ground 2
48MTR L-HPower Shift Motor L-H

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±30
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
StateUnit
Scale/
RangeMeasure
between
Pin No.Standard ValueNote
22P-GNDOFFSTOP
22, 47Continuity : OK
46GNDIOFFSTOP
46, 47Continuity : OK
47GND 2OFFSTOP
47, GNDContinuity : OK
314H SWOFFSTOP
31, 47No continuity
(high, 4L) : OK
444L SWOFFSTOP
44, 47No continuity
(high) and
continuity (4L) :
OK
42AXLE SWONRUN
42, 47Continuity(TOD,
4L) : OKRemove ECU connector and start
the engine. Move the vehicle forth
and back to connect axle surely.
29DIAGOFFSTOP
29 (TOD),
8 (DLC
Connec-
tor)Continuity : OKDLC connector terminal 8
7IND.AONSTOPDCV7 (+), 47
(±)8.0 ~14.5 Vwhen the indicator lamp is turned
off.
20CHECK
TODONSTOPDCV20 (+), 47
(±)8.0 ~14.5 VWhen the indicator lamp is turned
off.
33ABS INONSTOPDCV33 (+), 47
(±)6.0 ~11.0 V
12REFONSTOPDCV12 (+), 47
(±)5 ~9 VConnect ECU
32FRT.(+)ONSTOPDCV32 (+), 47
(±)0.7 ~6 VConnect ECU and move the
vehicle (off one tooth of speed
sensor ring) making sure of
voltage change.
45RR.(+)ONSTOPDCV45 (+), 47
(±)0.7 ~6 VConnect ECU and move the
vehicle (off one tooth of speed
sensor ring) making sure of
voltage change.
13COM(-)ONSTOPDCV13 (+), 47
(±)0VConnect ECU
14VIGONSTOPDCV14 (+), 47
(±)8 ~14.5 V
34VBOFFSTOPDCV34 (+), 47
(±)8.0 ~14.5 V
37BRAKE
SWOFFSTOPDCV37 (+), 47
(±)8 ~14.5 VPress brake pedal
15TPSONSTOPDCV15 (+), 47
(±)PWM duty cycle
10%(MAX) ± 90
%(MIN)Step on the accelerator pedal and
make sure that duty cycle
changes.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±102
Diagnosis from Symptom
Troubles that are not indicated by the warning lamp are
listed in the table below. These troubles are caused by the
faults that cannot be detected by the self-diagnostic
function of the control unit.
If this type of trouble is observed, interview the customer
and conduct test runs to reproduce the trouble,
cross-check the reported trouble with the listed
phenomena, and diagnose and analyze the trouble on the
item by item basis.
PhenomenaMajor causeCorrective action
1The tight corner braking is
observed when the vehicle is
subject to full steering.
The standard tires are not used.

The tire pressure is incorrect.

The tires are worn inuniformity.

The transfer or wiring is
imperfect.

The limited slip differential is
failed.Check and recondition the
vehicle according to Chart 1.
2Even if the TOD switch is selected
to the TOD position, the F4WD
mode is not active, resulting in
remarkable rear wheel spin.
The transfer or wiring is
imperfect.

The shift on the fly system is
failed.Check and recondition the
vehicle according to Chart 2.
3
When the TOD switch is
selected to the TOD position,
the drive resistance of the
F4WD system is too large to get
sufficient running speed.

Noised drive line.
The standard tires are not used.

The tires are worn inuniformity.

The transfer or wiring is
imperfect.

The limited slip differential is
failed. Check and recondition the
vehicle according to Chart 1.
4The shift on the fly system (front
axle disconnect) generates gear
noises.
The wiring is imperfect.

The shift on the fly system is
failed.Check and recondition the
vehicle according to Chart 3.
5The braking distance gets long
even when the ABS is active.
The wiring is imperfect.

The ABS is failed.Check and recondition the
vehicle according to Chart 4.
6The transfer does not change to the
low range from the high range.
The transfer or wiring is
imperfect.

The TOD switch is imperfect.

The AT inhibitor switch is
imperfect.
Check and recondition the
vehicle according to chart 5.
7The transfer does not change to the
high range from the low range.
im erfect.

The brake switch is imperfect.

The engine speed signal is
imperfect.

The speed sensor is imperfect.
Check and recondition the
vehicle according to chart 6.
8The transfer stays neutral and the
vehicle does not run.
The transfer is imperfect.Check and recondition the
vehicle according to chart 7.

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±104
StepActionYe sNo
1Are the front and rear tires in specified size?
Go to Step 2
Replace the tires
with specified
ones, and service
the new tires.
Go to
Step 16
2Is the tire pressure correct?
Go to Step 3
Inflate the tires
with specified
pressure.
Go to
Step 16
3Are the tires free from abnormal wear?
Go to Step 4
Replace the tires
with specified
ones, and service
the new tires.
Go to
Step 16
4Are different types of tires used?
Go to Step 5
Replace the tires
with specified
ones, and service
the new tires.
Go to
Step 16
51. Start the engine.
2. Select the TOD switch to the TOD position.
3. Fully turn the steering to the left (or right) end, and select the D
range and start the creep run.
Does the tight corner braking occur? Is the judder with chug-chug
sound observed? * Use caution on the operation.
Go to Step 6 Go to Step 11
61. Select the TOD switch to the 2H position.
2. Fully turn the steering to the left (or right) end, and select the D
range and start the creep run.
Does the tight corner braking occur? Is the judder with chug-chug
sound observed? * Use caution on the operation.
Go to Step 7 Go to Step 14
7Is an LSD mounted to the rear differential? Go to Step 8 Go to Step 9
8Is the genuine LSD oil used in the rear differential?
Go to Step 9
Replace the
differential oil.
Go to
Step 16
9Does the engine output the power correctly?
Go to Step 10
Check the
engine.
Go to
Step 16
10Do the speed sensors work correctly? (Check trouble codes.)The ECU has
failed. Replace
the ECU.
Go to
Step 16
Replace the
speed sensors.
Go to
Step 16
11Is the tight corner braking observed only when the brake is
applied?
Go to Step 12
Conduct full
steering under
WOT.
Go to
Step 5
121. Turn on the starter switch.
Is 8 ~ 10 V observed between terminals 33 and 47?
Go to Step 13
Repair the circuit
of the ECU
connector
terminal 33 (ABS
IN).
Go to
Step 16

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±110
Chart 4The braking distance gets long even when the ABS is active.
Function of circuitÐ
Fail conditionEnough deceleration is not obtained and the braking distance gets long even when the
ABS is active in the 2H mode.
D04R200021

DRIVE LINE CONTROL SYSTEM (TOD) 4B2–111
Step Action Yes No
1 Are the brake and ABS systems healthy?
Go to
Step 2
Repair the brake
and ABS. (Refer to
section 5A and 5B)
2 Turn on the star ter switch.
Is the battery voltage observed between terminals 14 and 47?
Go to
Step 3
Repair the
battery system.
Go to
Step 5
3 1. Select the TOD switch to the 2H position.
Does the voltage between terminals 36 and 47 range between
7.5 and 16V (0.12 seconds make a cycle)? Go to
Step 4
The ECU has
failed. Replace
the ECU.
Go to
Step 5
4 1. Turn off the starter switch.
2. Disconnect the connector (C–37).
Is there the continuity between the connector terminal (C–37) 14
and (C–6) 8?The
phenomenon is
not reproduced.
Refer to
“Trouble
intermittently
observed".
Repair the
harness.
Go to Step 5
5 Check that all the par ts are mounted.
Is this step complete? Verify the repair. Go to
Step 5