Isuzu 4HL1 Workshop Manual page 166

1A-164 Engine Control System
2. Turn on the idle position switch for not less than 1
second but not more than 3 seconds. (Release the
accelerator pedal.)
3. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
4. Turn on the idle position switch for not less than 1
second but not more than 3 seconds. (Release the
accelerator pedal.)
5. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
6. After the above operations are properly completed,
the CHECK ENGINE lamp (MIL) illuminates for 3
seconds to report the memory is cleared.
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.
Step
Perform the "On-Board Diagnostic (OBD)
System Check".
1
Was the OBD System Check performed?
Review the DTC.
1. Using Tech 2, check and store the DTC.
2. Clear the DTC.
2
3. Perform test run and review the DTC.
Is DTC82 detected?
Check the neutral (P/N) switch for operation.
1. Install Tech 2.
2. Starter switch "ON", and display the
engine data.
3
3. Observe the "Neutral Switch" display
while operating the shift lever.
Is the neutral switch turned on and off?
Check the neutral (P/N) switch circuit for +B
short.
1. Starter switch "OFF".
2. Disconnect the VIM.
4
3. At the VIM connector pins, measure the
resistance.
Was the resistance within range?
Action
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
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.
2. If the DTC is not detected, the possible cause is
intermittent (intermittent fault).
Value(s)
—
Go to Step 2
—
Go to Step 3
—
Go to Step 8
Pins 44-36/
38/75/76: ∞ Ω
Go to Step 5
at VIM: Inspect
Yes No
Refer to OBD
System Check
and go to Step 2
Refer to
Diagnostic Aids
Go to Step 4
Go to Step 7
harness