Dtc277 - Injector Power Supply System Open Wiring Fault (Common 1) - Isuzu 4HL1 Workshop Manual

DTC277 - Injector Power Supply System Open Wiring Fault (Common 1)

Circuit Description
The common 1 injector drive circuit is a high-voltage
system and drives injectors installed to cylinders 1 and
4. The ECM steps up the battery voltage and supplies
the resulted high voltage to the related injectors
continuously.
DTC277 will be set when open wiring occurs on the
common 1 injector drive circuit.
Major Faulty Event
• Short power
• Poor driveability
Conditions for Setting the DTC
Open wiring is detected between injector #1/3 and
ECM common 1 pin (both the drive circuits for injectors
#1 and #3 have open wiring).
Action Taken When the DTC Sets
• After the DTC is set, the ECM will illuminate the
CHECK ENGINE lamp (MIL).
• Fault judgment is disabled on injector drive circuit
for cylinders 1 and 4 and supply pump system.
• Only main injection is enabled.
• The calibrated
quantity becomes zero.
• Fuel injection at cylinders 1 and 4 is terminated.
23 5 4
24
Cylinder 2 Cylinder 3
cylinder-to-cylinder injection
2 1
42 43
Cylinder 4 Cylinder 1
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
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.
Engine Control System 1A-235
ECM
(Engine
Control
Module
LNW21AMF007001-X