Isuzu 4ja1, Workshop Manual

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Engine Control System (4JH1) 6E-75
DTC P0110 (Symptom Code 2) (Flash Code 23)
Circuit Description
The intake air temperature (IAT) sensor is fitted
between the air cleaner and turbocharger internal to the
mass air flow (MAF) sensor. The IAT sensor is a
variable resistor. The IAT sensor has a signal circuit
and a low reference circuit. The IAT sensor measures
the temperature of the air entering the engine. The
engine control module (ECM) supplies 5 volts to the IAT
signal circuit and a ground for the IAT low reference
circuit. When the IAT sensor is cold, the sensor
resistance is high. When the air temperature increases,
the sensor resistance decreases. With high sensor
resistance, the ECM detects a high voltage on the IAT
signal circuit. With lower sensor resistance, the ECM
detects a lower voltage on the IAT signal circuit. If the
ECM detects an excessively low IAT signal voltage, this
DTC will set.
Condition for Running the DTC
•
The ignition switch is ON.
Condition for Setting the DTC
•
The ECM detects that the IAT sensor signal
voltage is less than 0.3 volts for 3 seconds.
Action Taken When the DTC Sets
•
The ECM illuminates the malfunction indicator
lamp (MIL) when the diagnostic runs and fails.
•
The ECM uses an IAT substitution of 0
°
C (32
°
F)
for engine control.
Condition for Clearing the MIL/DTC
•
The ECM turns OFF the MIL when the diagnostic
runs and does not fail.
•
A history DTC clears after 40 consecutive driving
cycles without a fault. Or clear with the scan tool.
Diagnostic Aids
•
If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
•
Use the Temperature vs. Resistance table to test
the IAT sensor at various temperature levels to
evaluate the possibility of a skewed sensor. A
skewed sensor could result in poor driveability
concerns.
Notice:
•
The mass air flow (MAF) sensor is heated and as
a result the IAT sensor may indicate a higher than
normal intake temperature if the ignition switch is
being ON.
DTC P0110 (Symptom Code 2) (Flash Code 23)
Schematic Reference:
Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views
Step Action
Value(s)
Yes No
1 Did you perform the Diagnostic System Check-
Engine Controls?

Go to Step 2
Go to Diagnostic
System Check-
Engine Controls
2 1. Install the scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Observe the Intake Air Temperature (IAT)
parameter with the scan tool.
Is the IAT parameter more than the specified value?
110°C (230°F)
Go to Step 3
Go to Diagnostic
Aids
3 1. Turn OFF the ignition.
2. Disconnect the mass air flow/intake air
temperature (MAF/IAT) sensor harness
connector.
3. Turn ON the ignition, with the engine OFF.
4. Observe the IAT parameter with the scan tool.
Is the IAT parameter less than the specified value?
-38°C (-36°F)
Go to Step 5 Go to Step 4
4 1. Test the signal circuit between the engine control
module (ECM) (pin 3 of C-57 connector) and the
IAT sensor (pin 1 of C-116 connector) for the
following conditions:
•
A short to ground
•
A short to the low reference circuit
2. Repair the circuit(s) as necessary.
Did you find and correct the condition?

Go to Step 8 Go to Step 6