2002 ISUZU AXIOM ECU

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.

4B2±35
DRIVE LINE CONTROL SYSTEM (TOD)
Diagnostic Trouble Codes
CodeTech 2 code
(P code)ItemDiagnosisCheck flow No.
12ÐStart codeNormalÐ
13P1735RefShorted GND6
14P1731Front speed sensorInput abnormality (open, sig or com)2
15P1736RefShorted VB6
16P1737Front speed sensorInput abnormality4
17P1774Inhibitor switchInput abnormality8
21P1716TPSShorted or disconnected wiring,
abnormality in input7
23ÐECUCPU abnormality1
24P1733Rear speed sensorInput abnormality (open, sig or com)3
27P1738Rear speed sensorInput abnormality5
28P1760ADC (+) & AXLE SWOutput abnormality10
31P1721EMC (+)Shorted VB, disconnected coil/wiring or
shorted GND9
32P1761ADC (+)Shorted VB or disconnected wiring11
33P1762ADC (+)Shorted GND12
36ÐECUCPU abnormality1
37P1712ECUCPU abnormality1
38P1714ECUCPU abnormality1
41P1741Hight-Low shift motorShorted GND or disconnected wiring13
42P1773Hight-Low shift motorUser operation error (not failure)14
43P1743Hight-Low shift motorMotor moving more than 5s15
55P1755Hight-Low shift motorInput abnormality of motor position signal16
TPS : Throttle Position Sensor
EMC : Electromagnetic coil
ADC : Shift on the fly (Axle Dis Connect)

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±36
Diagnosis from Trouble Codes

Diagnose the fault that have been saved to the control
unit according to the system self-diagnostic function.
Check flow
Trouble codePhenomenonStandard
1 23, 36, 37, 38The ECU has failed.Ð
P1712, P1714
StepActionYe sNo
1Turn on the starter switch.
Is the trouble reproduced?Replace the ECU
and conduct the
test run.
Go to
Step 3Go 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
ªTrouble
intermittently
observedº.
Go to Step 3
31. Check that all the parts are mounted.
2. Clear the trouble codes.
Is this step complete?
Verify the repair.Return to Step 3

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±38
StepActionYe sNo
11. Start the engine.
2. Select TOD mode.
Is there the memory except DTC 14(P1731)?
Go to Step 4Go to Step 2
21. Turn off the starter switch.
2. Disconnect the ECU connector (C±38) and (C±37).
Is there the continuity between (C±37) terminal 10 and 25?
Repair the circuit.
Go to
Step 7Go to Step 3
31. Disconnect the transfer connector (A±1).
Is there the continuity between the connector (C±37) terminal 10
and the connector (A±1) terminal 6, the connector (C±38) terminal
12 and connector (A±1) terminal 2, and the connector (C±38)
terminal 13 and connector (A±1) terminal 10?
Replace the front
speed sensor.
Go to
Step 7
Repair the circuit.
Go to
Step 7
4Is the memory DTC 24(P1733)?
Go to Step 5
Refer to other
trouble check
flow.
5Is there the continuity between harnesses of terminal 32 and 45
(vehicle side terminal of the front and rear speed sensor)?
Go to Step 6
Repair the circuit.
Go to
Step 7
6Is there the continuity between harnesses of terminal 12 and 13
(vehicle side terminal of the speed sensor COM(±) and ref)?Replace front and
rear speed
sensor.
Go to
Step 7
Repair the circuit.
Go to
Step 7
71. Check that all the parts are mounted.
2. Clear the trouble code.
Is the step complete?
Verify the repair.Return to Step 7

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±40
StepActionYe sNo
11. Start the engine.
2. Select TOD mode.
Is there the memory except DTC 24(P1733)?
Go to Step 4Go to Step 2
21. Turn off the starter switch.
2. Disconnect the ECU connector (C±38) and (C±37).
Is there the continuity between the connector (C±37) terminal 23
and 25?
Repair the circuit.
Go to
Step 7Go to Step 3
31. Disconnect the transfer connector (A±1).
Is there the continuity between the connector (C±37) terminal 23
and the connector (A±1) terminal 5, the connector (C±38) terminal
12 and connector (A±1) terminal 1, and the connector (C±38)
terminal 13 and connector (A±1) terminal 9?
Replace the rear
speed sensor.
Go to
Step 7
Repair the circuit.
Go to
Step 7
4Is the memory DTC 14(P1731)?
Go to Step 5
Refer to other
trouble cheek
flow.
5Is there the continuity between harnesses of terminal 32 and 45
(vehicle side terminal of the front and rear speed sensor)?
Go to Step 6
Repair the circuit
Go to
Step 7
6Is there the continuity between harnesses of terminal 12 and 13
(vehicle side terminal of the speed sensor COM(±) and ref)?Replace front and
rear speed
sensor.
Go to
Step 7
Repair the circuit.
Go to
Step 7
71. Check that all the parts are mounted.
2. Clear the trouble code.
Is the step complete?
Verify the repairReturn to Step 7

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±42
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 6
21. Clear the trouble code.
While running at 40 km/h or 25 mph in TOD mode for 30
consecutive sec, is the trouble code reissued?
Go to Step 3
The trouble is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
31. Turn off the starter switch.
2. Disconnect the ECU connector (C±38) and (C±37).
Is there the continuity between the connector (C±37) terminal 10
and 25?
Repair the circuit.
Go to
Step 6Go to Step 4
41. Disconnect the transfer connector (A±1).
Is there the continuity between the connector (C±37) terminal 10
and the connector (A±1) terminal 6, the connector (C±38) terminal
12 and connector (A±1) terminal 2, and the connector (C±38)
terminal 13 and connector (A±1) terminal 10?
Replace the front
speed sensor.
Go to
Step 5
Repair the circuit.
Go to
Step 5
51. Clear the trouble code.
While running at 40 km/h or 25 mph in TOD mode for 30
consecutive sec, is the trouble code reissued?
Replace ECU.
Go to
Step 6Go to Step 6
61. Check that all the parts are mounted.
2. Clear the trouble code.
Is this step complete?
Repeat the
ªDiagnosis Flowº.
Return to Step 6