Isuzu 4HL1 Workshop Manual page 150

Engine control system
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1A-148 Engine Control System
1. Turn off the idle position switch for not less than 1
second but not more than 3 seconds. (Press the
accelerator pedal.)
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?
Check the exhaust brake solenoid valve
connector for installation and, if mounted
2
improperly, 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 DTC46 detected?
Check the exhaust brake solenoid valve
circuit.
1.
Starter switch "OFF".
2.
Disconnect the exhaust brake solenoid
4
valve connector.
3.
Jumper the harness connector pins.
4.
Use Step 3 and review the DTC
Is DTC46 detected?
Replace the exhaust brake solenoid valve.
5
Is the action complete?
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.
3. If the DTC is not detected, the possible cause is
intermittent (intermittent fault).
4. If even this step fails to detect the DTC, the exhaust
brake solenoid valve is faulty.
Value(s)
Go to Step 2
Go to Step 3
Go to Step 4
Go to Step 6
Verify repair and
go to Step 11
at
VIM:
Inspect
Yes
No
Refer to OBD
System Check
and go to Step 2
Refer to
Diagnostic Aids
Go to Step 5
harness

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