Kubota WG1605-E3, Diagnostic Manual

Page: 150 / 241

ECM SYSTEM
WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, DM
1-140
The Intake Air Temperature sensor is a thermistor (temperature sensitive resistor) located in the intake manifold
of the engine. It is used to monitor incoming air and the output, in conjunction with other sensors, is used to determine
the airflow to the engine. The ECM provides a voltage divider circuit so that when the air is cool, the signal reads
higher voltage, and lower when warm.
The Manifold Air Temperature is a calculated value based mainly on the IAT sensor at high airflow and influenced
more by the ECT/CHT at low airflow. It is used to monitor incoming air and the output, in conjunction with other
sensors, is used to determine the airflow to the engine, and ignition timing.
DTC 129-BP Low Pressure
• Hardware: Barometric Temperature/Manifold Absolute Pressure Sensor
• Enabling Conditions: Engine Running
• Set Conditions: BP pressure is less than 57.2 kPa [abs] (0.584 kgf/cm
2
, 8.30 psia) for longer than 1 sec.
• Corrective Action(s): Illuminate MIL, disable fuel adaptive learning while the code is active.
• Emissions related fault
• Possible Causes: Faulty ECM (no voltage on signal wire), signal wire shorted to ground or sensor internally
shorted
This fault sets if the barometric pressure is lower than the minimum set pressure (psia) as defined in the diagnostic
calibration. In the event of an active fault, the MIL is illuminated for the remainder of the key on cycle, an audible
warding and/or a secondary warning lamp is activated, and the Adaptive Learn function is disabled to prevent
improper learning and population of the table.
Barometric Pressure is estimated from the MAP sensor at key-on and in some calibrations during low speed/high
load operation as defined in the engine’s calibration. The barometric pressure value is used for fuel and airflow
calculations and equivalence ratio targets based on altitude.
DTC 111-IAT Higher Than Expected Stage 1
Diagnostic Aids
• This fault will set when inlet air is hotter than normal. The most common cause of high inlet air temperature is a
result of a problem with routing of the inlet air. Ensure inlet plumbing sources are external, is cool, and is not too
close to the exhaust at any point.
• Inspect the inlet air system for cracks or breaks that may allow unwanted underhood air to enter the engine.
• If no problem is found, replace the IAT sensor with a known good part and retest.
KiSC issued 12, 2016 A