Diagnostic Trouble Code (Dtc) P1111 - Isuzu 1999 RODEO Workshop Manual

6E1–306 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P1111 INTAKE AIR TEMPERATURE (IAT)
SENSOR CIRCUIT INTERMITTENT HIGH VOLTAGE
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 P1111 will set when the PCM
intermittently detects an excessively high signal voltage
on the intake air temperature sensor signal circuit. DTC
P1111 is a type D code.
Conditions for Setting the DTC
f The engine has been running for over 4 minutes.
f Vehicle speed is less than 32 km/h (20 mph).
f Engine coolant temperature is above 60°C (140°F).
f Calculated air flow is less than 20g/second.
f IAT signal voltage indicates an intake air temperature
intermittently less than –39°C (–38°F) (4.94 volts) for
approximately 2.5 seconds over a 25–second period of
time.
Action Taken When the DTC Sets
f The PCM will substitute a default value for intake air
temperature.
f The PCM will store conditions which were present
when the Diagnostic Trouble Code set as Failure
Records data only. This information will not be stored
as Freeze Frame data.
f Diagnostic Trouble Code P1111 does not illuminate the
MIL.
Conditions for Clearing the DTC
f A history DTC P1111 will clear after 40 consecutive
warm–up cycles have occurred without a fault.
f Diagnostic Trouble Code P1111 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 positive,
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.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the Diagnostic Trouble Code to
D06RX043