ECU ISUZU TROOPER 1998 Service Service Manual

4B2±59 DRIVE LINE CONTROL SYSTEM (TOD)
Chart AIndicator drive circuit
Function of circuitThe circuit informs the indicator of the working condition of the ECU.
Fail conditionAll the TOD indicator lamps and CHECK lamp are lit, and go off momentarily at an inter-
val of about two seconds.
Indicator lamp status
Ð
Transfer positionTOD, 4LÐ
D04RW062

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±60
StepActionYe sNo
1Turn on the starter switch.
Is the battery voltage observed between terminals 1 and 19?The ECU has
failed. Replace
the ECU.
Go to Step 2
Check the battery
circuit.
Go to Step 2
2Check that all the parts are mounted.
Is this step complete?Repeat the
ªDiagnosis Flowº.
Go to Step 2

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±62
StepActionYe sNo
11. Turn on the starter switch.
When the 4WD SW is selected to the 4WD position, is 0 V
observed between terminal 12 and 19?
Go to Step 2
Repair the 4WD
SW circuit.
Go to Step 4
2When the 4WD SW is selected to the 2WD position, is 12 V
observed between terminals 12 and 19?
Go to Step 3
Repair the 4WD
SW circuit.
Go to Step 4
3When the transfer lever is shifted to the 4L position, is battery
boltage observed between terminals 28 and 19?The phenomenon
is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
Go to Step 4
Replace the
ECU.
Go to Step 4
4Check that all the parts are mounted.
Is this step complete?Repeat the
ªDiagnosis Flowº.
Return to Step 4

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±64
StepActionYe sNo
1When the 4WD SW is selected to the 4WD position, is 0 V
observed between terminal 12 and 19?
Go to Step 2
Repair the 4WD
SW circuit.
Go to Step 7
2When the 4WD SW is selected to the 2WD position, is 12 V
observed between terminals 12 and 19?
Go to Step 3
Repair the 4WD
SW circuit.
Go to Step 7
31. Disconnect the ECU connector.
Is the continuity established between terminals (B±67)1 and
(B±68)13?
Go to Step 4
Replace TOD
indicator lamp
bulb.
Go to Step 7
4Is the continuity established between terminals (B±67)1 and
(B±68)14?
Go to Step 5
Replace TOD
indicator lamp
bulb.
Go to Step 7
5Is the continuity established between terminals (B±67)1 and
(B±68)15?
Go to Step 6
Replace TOD
indicator lamp
bulb.
Go to Step 7
6Is the continuity established between terminals (B±67)1 and
(B±68)16?
Replace ECU.
Go to Step 7
Replace TOD
indicator lamp
bulb.
Go to Step 7
7Check that all the parts are mounted.
Is this step complete?Repeat the
ªDiagnosis Flowº.
Return to Step 7

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±66
StepActionYe sNo
11. Turn on the starter switch.
When the transfer lever is shifted to the high position, is 5V
observed between terminals 8 and 19 (4H switch)?
Go to Step 2Go to Step 4
2When the transfer lever is shifted to the 4L position, is 5V
observed between terminals 8 and 19 (4H switch)?
Go to Step 3Go to Step 4
3When the transfer lever is shifted to the neutral position, is 0V
observed between terminals 8 and 19 (4H switch)?Replace the
ECU.
Go to Step 4
Go to Step 4
41. Turn off the starter switch.
2. Disconnect the ECU connector.
3. Turn on the starter switch.
When the transfer lever is shifted to the high position, is 12V
observed between terminals 8 and 19 (4H switch)?
Go to Step 5Go to Step 7
5When the transfer lever is shifted to the neutral position, is 0V
observed between terminals 8 and 19 (4H switch)?
Go to Step 6Go to Step 7
6When the transfer lever is shifted to the 4L position, is 12V
observed between terminals 8 and 19 (4H switch)?The 4H switch
circuit battery is
short-circuited
between ECU
and transfer.
Repair the circuit.
Go to Step 14
Go to Step 7
7Turn off the starter switch.
When the transfer lever is shifted to the neutral position, is the
continuity established between terminals 8 and 19 (4H switch)?
Go to Step 8Go to Step 10
8When the transfer lever is shifted to the high position, is the
continuity established between terminals 8 and 19?
Go to Step 10Go to Step 9
9When the transfer lever is shifted to the 4L position, is the
continuity established between terminals 8 and 19?
Go to Step 14
The phenomenon
is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
Go to Step 10
10When the transfer lever is shifted to the neutral position, is the
continuity established between terminals (A±3)4 and (A±3)7?
Go to Step 11
Repair the
transfer
assembly.
Go to Step 14
11When the transfer lever is shifted to the high position, is the
continuity established between transfer connector terminals
(A±3)4 and (A±3)7?Repair the
transfer
assembly.
Go to Step 14
Go to Step 12
12When the transfer lever is shifted to the 4L position, is the
continuity established between transfer connector terminals
(B±68)3 and (A±3)4?Repair the
transfer
assembly.
Go to Step 14
Go to Step 13

4B2±67 DRIVE LINE CONTROL SYSTEM (TOD)
StepNo Ye s Action
13Is the continuity established between transfer terminals (A±3)4
and body?
The ECU has
failed. Replace
the ECU.
Go to Step 14
The harness is
broken between
terminal (A±3)4
and GND. Repair
the circuit.
Go to Step 14
14Check that all the parts are mounted.
Is this step complete?Repeat the
ªDiagnosis Flowº.
Return to Step 14

4B2±69 DRIVE LINE CONTROL SYSTEM (TOD)
StepActionYe sNo
1When the transfer lever is shifted to the High position, is 5V
observed between terminals 8 and 19 (4H switch)?
Go to Step 2Go to Step 14
2When the transfer lever is shifted to the neutral position, is 0V
observed between terminals 8 and 19 (4H switch)?
Go to Step 3Go to Step 14
3When the transfer lever is shifted to the 4L position, is 5V
observed between terminals 8 and 19 (4H switch)?
Go to Step 4Go to Step 14
41. Turn off the starter switch.
Is the continuity established between terminals 1 and 25?
Go to Step 5
Replace TOD
indcator lamp
bulb.
Go to Step 23
5Is the continuity established between terminals 1 and 26?
Go to Step 6
Replace TOD
indicator lamp
bulb.
Go to Step 23
6Is the continuity established between terminals 1 and 27?
Go to Step 7
Replace TOD
indicator lamp
bulb.
Go to Step 23
7Is the continuity established between terminals 1 and 28?
Go to Step 8
Replace TOD
indicator lamp
bulb.
Go to Step 23
8Is the continuity established between terminals 1 and 29?
Go to Step 9
Replace TOD
indicator lamp
bulb.
Go to Step 23
91. Turn on the starter switch.
2. Shift the transfer lever is shifted to the 4L position.
Is 0 V observed between terminals 25 and 20?
Go to Step 10
The ECU has
failed. Replace
the ECU.
Go to Step 23
10Is 0 V observed between terminals 26 and 20?
Go to Step 11
The ECU has
failed. Replace
the ECU.
Go to Step 23
11Is 0 V observed between terminals 27 and 20?
Go to Step 12
The ECU has
failed. Replace
the ECU.
Go to Step 23
12Is 12 V observed between terminals 28 and 20?
Go to Step 13
The ECU has
failed. Replace
the ECU.
Go to Step 23
13Is 0 V observed between terminals 29 and 20?The phenomenon
is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
Go to Step 23
The ECU has
failed. Replace
the ECU.
Go to Step 23

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±70
StepNo Ye s Action
141. Turn off the starter switch.
2. Disconnect the ECU connector.
When the transfer lever is shifted to the neutral position, is the
continuity established between terminals (B±68)3 and (B±67)11
(4H switch)?
Go to Step 15Go to Step 17
15When the transfer lever is shifted to the high position, is the
continuity established between terminals (B±68)3 and (B±67)11?
Go to Step 17Go to Step 16
16When the transfer lever is shifted to the 4L position, is the
continuity established between terminals (B±68)3 and (B±67)11?The ECU has
failed. Replace
the ECU.
Go to Step 23
Go to Step 17
171. Disconnect the H±49 connector.
When the transfer lever is shifted to the neutral position between
high and 4L, is the continuity established between terminals
(H-49)6 and (B-68)3?
Go to Step 18Go to Step 20
18When the transfer lever is shifted to the high position, is the
continuity established between transfer connector terminals
(H-49)6 and (B-68)3?
Go to Step 20Go to Step 19
19When the transfer lever is shifted to the 4L position, is the
continuity established between transfer connector terminals
(H-49)6 and (B-68)3?
Go to Step 20
GND is
short-circuited
between
terminals (B-68)3
and (H-49)6.
Repair the circuit.
Go to Step 23
201. Disconnect the A±3 connector.
When the transfer lever is shifted to the neutral position between
high and 4L, is the continuity established between terminals
(A-3)4 and (B-68)3?
Go to Step 21
Repair the
transfer
assembly.
Go to Step 23
21When the transfer lever is shifted to the high position, is the
continuity established between terminals (A-3)4 and (B-68)3?Repair the
transfer
assembly.
Go to Step 23
Go to Step 22
22When the transfer lever is shifted to the 4L position, is the
continuity established between terminals (A-3)4 and (B-68)3?
Repair the
transfer
assembly.
Go to Step 23
GND is
short-circuited
between
terminals (B-68)3
and (A±3)4.
Repair the circuit.
Go to Step 23
23Check that all the parts are mounted.
Is this step complete?Repeat the
ªDiagnosis Flowº.
Return to Step 23

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±72
StepActionYe sNo
1Turn on the starter switch.
When the transfer lever is shifted to the high position, is 5V
observed between terminals 9 and 19 (4L switch)?
Go to Step 2Go to Step 4
2When the transfer lever is shifted to the neutral position, is 0V
observed between terminals 9 and 19 (4L switch)?
Go to Step 3Go to Step 4
3When the transfer lever is shifted to the 4L position, is 0V
observed between terminals 9 and 19 (4L switch)?The ECU has
failed. Replace
the ECU.
Go to Step 4
Go to Step 4
41. Turn off the starter switch.
2. Disconnect the ECU connector.
3. Turn on the starter switch.
When the transfer lever is shifted to the high position, is 12V
observed between terminals (B±68)4 and (B±67)11?
Go to Step 5Go to Step 7
5When the transfer lever is shifted to the neutral position, is 0V
observed between terminals (B±68)4 and (B±67)11?
Go to Step 6Go to Step 7
6When the transfer lever is shifted to the 4L position, is 0V
observed between terminals (B±68)4 and (B±67)11?The 4L switch
circuit battery is
short-circuited
between ECU
and transfer.
Repair the circuit
Go to Step 13
Go to Step 7
7Turn off the starter switch.
When the transfer lever is shifted to the high position, is the
continuity established between terminals (B±68)3 and (B±67)11?
Go to Step 10Go to Step 8
8When the transfer lever is shifted to the neutral position between
high and 4L, is the continuity established between terminals
(B±68)4 and (B±67)11?
Go to Step 9Go to Step 10
9When the transfer lever is shifted to the 4L position, is the
continuity established between terminals (B±68)4 and (B±67)11?The phenomenon
is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
Go to Step 13
Go to Step 10
101. Disconnect the A±3 connector.
When the transfer lever is shifted to the neutral position between
high and 4L, is the continuity established between transfer
connector terminals (A±3)12 and GND?Wires are broken
between transfer
connector (A±3)
and floor
connector (H-49).
Repair the circuit.
Go to Step 11
Repair the
transfer
assembly.
Go to Step 13
11When the transfer lever is shifted to the 4L position, is the
continuity established between transfer connector terminals
(A±3)12 and GND?
Go to Step 12
Repair the
transfer
assembly.
Go to Step 13
12When the transfer lever is shifted to the high position, is the
continuity established between transfer connector terminals
(A±3)12 and GND?Repair the
transfer
assembly.
Go to Step 13
Go to Step 13
13Check that all the parts are mounted.
Is this step complete?Repeat the
ªDiagnosis Flowº.
Return to Step 13

DRIVE LINE CONTROL SYSTEM (TOD) 4B2±74
StepActionYe sNo
1When the transfer lever is shifted to the high position, is 5V
observed between terminals 9 and 19 (4L switch)?
Go to Step 2Go to Step 7
2When the transfer lever is shifted to the neutral position, is 0V
observed between terminals 9 and 19 (4L switch)?
Go to Step 3Go to Step 7
3When the transfer lever is shifted to the 4L position, is 0V
observed between terminals 9 and 19 (4L switch)?
Go to Step 4Go to Step 7
41. Shift the 4WD SW to the 2H position.
Is 12V observed between terminals 25 and 19?
Go to Step 5
The ECU has
failed. Replace
the ECU.
Go to Step 16
5Is 12V observed between terminals 26 and 19?
Go to Step 6
The ECU has
failed. Replace
the ECU.
Go to Step 16
6Is 12V observed between terminals 27 and 19?The phenomenon
is not
reproduced.
Refer to
ªTroubles
intermittently
observedº.
Go to Step 16
The ECU has
failed. Replace
the ECU.
Go to Step 16
71. Turn off the starter switch.
2. Disconnect the ECU connector.
When the transfer lever is shifted to the neutral position between
High and 4L, is the continuity established between terminals
(B±68)4 and (B±67)11?
Go to Step 8Go to Step 10
8When the transfer lever is shifted to the 4L position, is the
continuity established between terminals (B±68)4 and (B±67)11?
Go to Step 9Go to Step 10
9When the transfer lever is shifted to the high position, is the
continuity established between terminals (B±68)4 and (B±67)11?
Go to Step 10
The ECU has
failed. Replace
the ECU.
Go to Step 16
101. Disconnect the H-49 connector.
When the transfer lever is shifted to the neutral position between
high and 4L, is the continuity established between terminals
(H-49)5 and (B-67)11?
Go to Step 11Go to Step 13
11When the transfer lever is shifted to the 4L position, is the
continuity established between transfer connector terminals
(H-49)5 and (B-67)11?
Go to Step 12Go to Step 13
12When the transfer lever is shifted to the high position, is the
continuity established between terminals (H-49)5 and (B-67)11?
Go to Step 13
GND is
short-circuited
between
terminals (B±68)4
and (H-49)5.
Repair the circuit.
Go to Step 16
131. Disconnect the A-3 connector.
When the transfer lever is shifted to the neutral position between
high and 4L, is the continuity established between terminals
(A-3)12 and GND?
Go to Step 14
Repair the
transfer
assembly.
Go to Step 16