Dtc45 - Egr Valve System Fault - Isuzu 4HL1 Workshop Manual

1A-144 Engine Control System

DTC45 - EGR Valve System Fault

Circuit Description
The EGR valve is operated by the DC motor. The DC
motor changes the drive duty to operate the valve, and
increasing the duty opens the valve while decreasing
the duty closes the valve. The ECM calculates the
desired EGR valve position according to the current
vehicle running condition and controls the DC motor.
DTC45 will be set when the difference between desired
and actual EGR valve positions is excessively large or
the drive voltage is excessively high.
Major Faulty Event
• Generation of black smoke
• Short power
• Poor driveability
Conditions for Setting the DTC
The state where the EGR valve position sensor is in
normal condition and the valve drive voltage is
excessively high lasts for at least 10 seconds.
Action Taken When the DTC Sets
• After the DTC is set, the ECM will illuminate the
CHECK ENGINE lamp (MIL).
• EGR and intake throttle systems are disabled.
• The EGR motor is deenergized.
16 58 59
35
M M
M-
M- M+
M+
Intake
EGR
Throttle DC Motor
DC Motor
Conditions for Clearing MIL/DTC
When the system fails and the DTC is stored to the
ECM, even repairing the faulty portion will not clear the
DTC from the memory. To clear the DTC, conduct the
following steps.
1. Turn off the idle position switch for not less than 1
2. Turn on the idle position switch for not less than 1
3. Turn off the idle position switch for not less than 1
4. Turn on the idle position switch for not less than 1
5. Turn off the idle position switch for not less than 1
6. After the above operations are properly completed,
7. Turn off the starter switch. Wait for 5 seconds and
When Tech 2 has been connected to the vehicle, the
DTC can be cleared through the memory clear
operation with Tech 2.
ECM
(Engine
Control
Module)
second but not more than 3 seconds. (Press the
accelerator pedal.)
second but not more than 3 seconds. (Release the
accelerator pedal.)
second but not more than 3 seconds. (Press the
accelerator pedal.)
second but not more than 3 seconds. (Release the
accelerator pedal.)
second but not more than 3 seconds. (Press the
accelerator pedal.)
the CHECK ENGINE lamp (MIL) illuminates for 3
seconds to report the memory is cleared.
turn on the starter switch again.
LNW21AMF007301-X