Isuzu 4HL1, Workshop Manual

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1A-62 Engine Control System
Menu Breakdown
Diagnostic Trouble Codes
• When you find a DTC, go to the DTC Chart.
The DTC is a language allowing you to communicate
with the on-board ECM. The DTC is coarsely divided
into two categories, past DTC and current DTC.
• Current DTC: A fault (failure) is displayed that is
found in the current ignition cycle.
• Past DTC: A fault (failure) is displayed that was
found in the last or past ignition cycle.
• Multiple DTC is generated when several troubles
(failures) occur. When multiple sensors or switches
share a ground, or an open wiring or short occurs
on the shared power supply or ground, DTCs with
respect to related sensors or switches are
displayed. If several DTCs are displayed, it is
necessary to inspect the shared power supply or
ground for open wiring or short. Using DTC clear
mode erases the vehicle DTC information from the
ECM.
Data Display
• Typical values are described in the Tech 2 data
list.
This menu displays the current data. The contents
synchronize with the vehicle status. For example, the
engine coolant temperature sensor is monitored and
displayed on the screen and, if the engine is idling, the
temperature on the screen will be changed accordingly.
• When you cannot select this data display menu:
A fault presents on the cable between ECM and
DLC.
• When an unusual value appears fixedly:
Example - If the engine coolant temperature
displayed is fixed to –40°C or +140°C, the possible
cause is faulty ECT sensor, open wiring, or short.
When moving connectors or wiring harnesses with
hands changes the display, poor pin connection,
improper pin layout, broken harness wires, or short
is a cause and, therefore, repair is needed.
• When "
✻
" appears instead of value:
The Tech 2 software is faulty.
If even one asterisk is observed instead of data on
the display, the PCMCIA card needs version up.
Snapshot
• The snapshot mode records menus on the data list
and plots graphs.
• Using this mode, you can reproduce and record
customer’s claimed conditions and find faulty
engine data.
• You can replay the recorded data with the
commercial power applied to home outlets.
F2: Snaphot
F3: Actuator Test
F0: Common Rail Pressure Control Test
F1: Injector Balance Test
F2: Intake Throttle Test
F3: EGR Control Test
F4: Glow Time Relay Test
F0 : Read DTC Info As Stored By ECU
F1 : Clear DTC Information
Diagnostic Trouble Codes
LNW21ASH001501-X
LNW21ASH010601-X
S e l e c t
I t e m s
D T C
Quick
Snapshot
More
System Voltage
Vehicle Speed
Desired Idle Speed
Engine Speed
Accelerator Sensor
Final Accelerator Opening
ECT Sensor (Engine Coolant Temparature)
Coolant Temperature
System Voltage
Data Display
V
km/h
RPM
RPM
V
%
V
C