Isuzu 4HL1 Workshop Manual page 206

1A-204 Engine Control System
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.
Step
Perform the "On-Board Diagnostic (OBD)
System Check".
1
Was the OBD System Check performed?
Check the idle position switch for mechanical
fault.
1. Check the idle position switch connector
for installation and, if mounted improperly,
install the device certainly.
2. Check the contact between accelerator
pedal and switch and recondition the
2
improper contact, if any.
3. Press the idle position switch with a finger
to check the sliding performance. In case
of unsmooth movement, blow air against
the switch to remove foreign materials.
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 DTC241 detected?
Check the display on Tech 2.
1. Starter switch "ON", and display the
engine data.
2. Observe the "Idle Position Switch" display
4
while operating the accelerator pedal.
Is the idle position switch turned on and off
according to the pedal operation?
Check the idle position switch.
1. Starter switch "OFF".
2. Measure the resistance between the idle
5
position switch connector pins while
operating the switch with a finger.
Was the resistance within range?
Replace the idle position switch.
6
Is the action complete?
at ECM: Inspect
Action
• Damaged harness: Inspect the wiring harness for
rubbed-through wire insulation or wire broken
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
harness
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).
Value(s)
—
—
—
—
Switch-on
(switch is
released):
50 Ω, max.
Switch-off
(switch is
pressed): ∞ Ω
—
Yes
Refer to OBD
System Check
Go to Step 2 and go to Step 2
Go to Step 3
Go to Step 4 Diagnostic Aids
Go to Step 11 Go to Step 5
Go to Step 7 Go to Step 6
Go to Step 13
No
—
Refer to
—