Isuzu 4JA1 Workshop Manual page 292

6E-38 Engine Control System (4JH1)
Intake Air Temperature
This parameter displays the temperature of the intake
air based on a voltage input from the intake air
temperature (IAT) sensor to the ECM. The scan tool will
display a low temperature when signal voltage is high,
and high temperature when the signal voltage is low.
Note that the IAT sensor is internal to the mass air flow
(MAF) sensor and the MAF sensor is heated.
Engine Coolant Temperature
This parameter displays the temperature of the engine
coolant based on a voltage input from the engine
coolant temperature (ECT) sensor to the ECM. The
scan tool will display a low temperature when the signal
voltage is high, and a high temperature when the signal
voltage is low.
Fuel Temperature
This parameter displays the temperature of the fuel as
calculated by the fuel injection pump control unit (PCU)
using the signal from the fuel temperature sensor inside
of the PCU.
Barometric Pressure
This parameter displays the barometric pressure as
calculated by the ECM using the signal from the
barometric pressure (BARO) sensor inside of the ECM.
Vacuum Pressure
specification only)
This parameter displays the amount of the vacuum
pressure to the turbocharger wastegate valve. When a
high vacuum pressure at a low vacuum pressure
amount to the turbocharger wastegate valve. The scan
tool will display doubled barometric pressure when the
ignition is ON with the engine OFF.
Turbocharger Solenoid Command (High altitude
specification only)
This parameter displays the turbocharger solenoid
valuve control duty ratio commanded by the ECM
terminal (pin 18 of C-57) using the signal from various
sensor inputs. When a low duty ratio, vacuum pressure
to the turbocharger wastegate valve is controlled to
increase. When a high duty ratio, vacuum pressure to
the turbochager wastegate valve is controlled to reduce.
EGR Solenoid Command
This parameter displays the EGR solenoid valve control
duty ratio commanded by the ECM terminal (pin 19 of
C-57) using the signal from engine speed, and injection
volume and various sensor inputs. When a small duty
ratio, the EGR valve is controlled to close. When a large
duty ratio, the EGR valve is controlled to open.
Sensor (High altitude
Mass Air Flow Sensor
This parameter displays the air flow into the engine as
calculated by the ECM based on the mass air flow
(MAF) sensor input. The scan tool will display a high
value at higher engine speeds, and a low value at idle.
This can be compared to the Desired Mass Air Flow to
determine MAF sensor accuracy, EGR problem or
intake problem. Note that the MAF on the scan tool will
only update with the engine running.
Desired Mass Air Flow
This parameter displays a mass air flow desired by the
ECM based on current driving condition.
Actual Injection Quantity
This parameter displays the injection quantity calculated
by the PCU based on the fuel injection solenoid valve
On time which compensated from the timing device
position and fuel temperature inputs. This can be
compared to the Desired Injection Quantity to determine
fuel system problem.
Desired Injection Quantity
This parameter displays an injection quantity desired by
the ECM based on current driving condition using target
injection maps.
Actual Injection Timing
This parameter displays the injection timing calculated
by the PCU based on the timing device position which
determined from the crankshaft position sensor and
camshaft position sensor inputs. This can be compared
to the Desired Injection Timing to determine timing
device problem or fuel system problem.
Desired Injection Timing
This parameter displays injection timing desired by the
ECM based on current driving condition using target
injection timing maps. This timing is compensated by
engine coolant temperature, altitude and intake air
temperature, etc.
Neutral Switch
This parameter displays the state of the neutral switch
as determined by the ECM terminal (pin 6 of C-57)
based on an input from the neutral switch or inhibitor
switch.
Brake Pedal 1 Switch
This parameter displays the state of the brake pedal as
determined by the ECM terminal (pin 27 of C-56) based
on an input from the brake pedal 1 switch. This switch
turns On the stop lamps when the brake pedal is
depressed. The scan tool will display Applied when the
brake pedal is depressed.