Diagnostic Trouble Code (Dtc) P0112 Intake Air Temperature (Iat) Sensor Circuit Low Input - Isuzu 1999 RODEO Workshop Manual

6E1–120 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0112 INTAKE AIR TEMPERATURE (IAT)
Circuit Description
The intake air temperature (IAT) sensor is a thermistor
which measures the temperature of the air entering the
engine. The powertrain control module (PCM) applies 5
volts through a pull–up resistor to the IAT sensor. When
the intake air is cold, the sensor resistance is high and the
PCM will monitor a high signal voltage on the IAT signal
circuit. If the intake air is warm, the sensor resistance is
lower, causing the PCM to monitor a lower voltage.
Diagnostic Trouble Code P0112 will set when the PCM
detects an excessively low signal voltage (short to
ground) on the intake air temperature sensor signal
circuit. DTC P0112 is a Type A Code.
Conditions for Setting the DTC
f The engine has been running for over 2 minutes.
f Vehicle speed is greater than 48 km/h (30 mph).
f IAT signal voltage less than 0.10 volts for a total of 12.5
seconds over a 25–second period of time.
The above conditions are met for at least 2 seconds.
Action Taken When the DTC Sets
f The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
f The PCM will use a default IAT valve based on PCM
inputs and engine run time.
SENSOR CIRCUIT LOW INPUT
f The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
f The PCM will turn the MIL OFF on the third consecutive
trip cycle during which the diagnostic has been run and
the fault condition is no longer present.
f A history DTC P0112 will clear after 40 consecutive
warm–up cycles have occurred without a fault.
f DTC P0112 can be cleared by using the Scan Tool's
"Clear Info" function.
Diagnostic Aids
Check for the following conditions:
f Poor connection at PCM – Inspect harness connectors
for backed–out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal–to–wire connection.
f Damaged harness – Inspect the wiring harness for
damage, shorts to ground, shorts to battery and open
circuits. If the harness appears to be OK, observe the
IAT display on the Tech 2 while moving connectors and
wiring harnesses related to the IAT sensor. A change
in the IAT display will indicate the location of the fault.
If Diagnostic Trouble Code P0112 cannot be duplicated,
the information included in the Failure Records data can
be useful in determining vehicle mileage since the
Diagnostic Trouble Code was last set.
D06RX043