Dtc247 - Scv Drive System Fault - Isuzu 4HL1 Workshop Manual

DTC247 - SCV Drive System Fault

Circuit Description
The SCV (suction control valve) is installed to the
supply pump and controls the suction fuel quantity. The
SCV is fully opened in normal state and larger drive
current (duty) results in smaller opening. The ECM,
based on the data acquired from sensors, calculates
desired common rail pressure and pump flow rate and
compares the calculated desired common rail pressure
to the actual value to determine the SCV position.
When the actual pressure is lower than the desired
value, the SCV is opened to increase the pump flow
rate. When the actual pressure is higher than the
desired value, the SCV is closed to decrease the flow
rate.
DTC247 will be set when the drive current is
excessively high or low or the difference between
desired and actual drive currents is large.
Major Faulty Event
• Poor startability
• Generation of white/black smoke
• Short power
• Poor driveability
Conditions for Setting the DTC
The SCV drive current is 1100 mA or less. (Short to
ground between SCV+ and ECM, +B short between
75 74 81 80
SCV
SCV– and ECM, short to ground between SCV– and
ECM, or open wiring between SCV and ECM is not
detected.)
Action Taken When the DTC Sets
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
Engine Control System 1A-215
ECM
(Engine
Control
Module)
• After the DTC is set, the ECM will illuminate the
CHECK ENGINE lamp (MIL).
• The common rail pressure and fuel injection
quantity are limited.
• Fault judgment is disabled on supply pump
overpressure and short pump pressure events 1 to
4.
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.)
LNW21AMF007201-X