Isuzu 4HL1 Workshop Manual page 53

Step
Perform the "On-Board Diagnostic (OBD)
System Check".
1
Was the OBD System Check performed?
Check other lamps in the meter (such as
parking brake lamp and charge lamp) are
turned on.
1. Starter switch "ON".
2
2. Check the lamp power-on status in the
meter.
Are other lamps "ON"?
Check the SBF (key switch: 50 A) and fuse
(meter back: 15 A).
3
Are SBF and fuse in normal condition?
Replace the SBF or fuse.
4
Is the action complete?
Check the power is supplied to the SBF (key
switch: 50 A).
1. Remove the SBF.
2. Starter switch "ON".
5
3. Measure
connector.
Was the voltage within range?
Check the battery voltage for correctness.
6
Is the battery voltage is normal condition?
Charge or replace the battery.
7
Is the action complete?
Check battery cables for poor connection or
open wiring.
8
Are battery cables in normal condition?
Repair or replace battery cables.
9
Is the action complete?
Check the power is supplied to the fuse
(meter back: 15 A).
1. Remove the fuse.
2. Starter switch "ON".
10
3. Measure
connector.
Was the voltage within range?
Repair or replace the harness between fuse
(meter back: 15 A) and CHECK ENGINE
11
lamp.
Is the action complete?
Action
the voltage at the
the voltage at the
Value(s)
—
—
—
—
16 ~ 32V
SBF
16 ~ 32V
—
—
—
16 ~ 32V
fuse
—
Engine Control System 1A-51
Yes
Go to Step 2
Refer to "ECM
Power Supply and
Grounding
System Circuit
Check" and go to
Step 19
Go to Step 5
Verify repair and
go to Step 23
Go to Step 10
Go to Step 8
Verify repair and
go to Step 23
Go to Step 23
Verify repair and
go to Step 23
Go to Step 11
Verify repair and
go to Step 23
No
Refer to OBD
System Check
and go to Step 2
Go to Step 3
Go to Step 4
—
Go to Step 6
Go to Step 7
—
Go to Step 9
—
Go to Step 12
—