Isuzu 4HL1 Workshop Manual page 110

1A-108 Engine Control System
7. Turn off the starter switch. Wait for 5 seconds and
turn on the starter switch again.
When Tech 2 has been connected to the vehicle, the
DTC can be cleared through the memory clear
operation with Tech 2.
Diagnostic Aids
Poor connection or damaged harness may cause
intermittents. Check for the following conditions and, if
the fault is detected, repair or replace the faulty portion.
• Poor connection
connectors for backed-out pins, improper mating,
broken locks, improperly formed or damaged pins,
and poor pin-to-wire connection.
• Damaged harness: Inspect the wiring harness for
rubbed-through wire insulation or wire broken
Step
Perform the "On-Board Diagnostic (OBD)
System Check".
1
Was the OBD System Check performed?
Check the
installation
2
connect it certainly.
Is the action complete?
Review the DTC.
1. Using Tech 2, check and store the DTC.
2. Clear the DTC.
3
3. Perform test run and review the DTC.
Is DTC23 detected?
Check multiple DTCs are set.
4
Is DTC211 (Fuel Temperature Sensor System
Fault) detected together with DTC23?
Check the ground circuit common to ECT and
FT sensors for +B short.
1. Starter switch "OFF".
2. Disconnect the ECM.
5
3. At the ECM connector pins, measure the
resistance.
Was the resistance within range?
Repair or replace the faulty harness.
6
Is the action complete?
at ECM: Inspect
Action
ECT sensor connector
and, if mounted improperly,
inside the insulator. If the harness appears to be
OK, observe the display on Tech 2 while moving
connectors and wiring harnesses related to the
sensor. A change in the display will indicate the
location of the fault.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
3. If the DTC is not detected, the possible cause is
intermittent (intermittent fault).
harness
4. If DTC211 is also set, the possible cause is the
ground circuit common to ECT and FT sensors.
10. If the output voltage is fixed to 5 V, the possible
cause is open wiring in the circuit. If the output voltage
is fixed to 0 V, the possible cause is short in the circuit.
Value(s)
—
for
—
—
—
Pins 46-109/
114/115/116:
∞ Ω
—
Yes
Go to Step 2 and go to Step 2
Go to Step 3
Go to Step 4 Diagnostic Aids
Go to Step 5
Go to Step 7
Verify repair and
go to Step 9
No
Refer to OBD
System Check
—
Refer to
Go to Step 10
Go to Step 6
—