DIAGNOSTIC MANUAL
Interstage Cooler (ISC)
Uses cooled coolant to lower the charged air temperature that exits from the turbocharger low-pressure
compressor and enters the turbocharger high-pressure compressor.
Low temperature radiator
thermostat
Coolant flow to the low temperature radiator is regulated by the low temperature radiator thermostat.
Lug (engine)
When the engine is run at an overly low RPM for the load being applied.
Manifold Absolute Pressure
(MAP)
Boost pressure in the manifold that is a result of the turbocharger.
Manifold Absolute Pressure
(MAP) sensor
A variable capacitance sensor that measures boost pressure.
Manometer
A double-leg liquid-column gauge, or a single inclined gauge, used to measure the difference between two
fluid pressures. Typically, a manometer records in inches of water.
Mass Air Flow
The intake airflow in an engine.
Mass Air Flow (MAF) sensor
The MAF sensor is used for closed loop control of the EGR valve and ITV. The ECM monitors the MAF
signal so that the ECM can control the EGR and intake throttle systems.
Magnehelic Gauge
A gauge that measures pressure in inches of water.
Magnetic Pickup Sensor
A magnetic pickup sensor generates an alternating frequency that indicates speed. Magnetic pickups have
a two-wire connection for signal and ground. This sensor has a permanent magnetic core surrounded by a
wire coil. The signal frequency is generated by the rotation of the gear teeth that disturb the magnetic field.
Metering unit valve assembly
The Metering unit valve assembly provides a metered amount of fuel to the Aftertreatment Fuel Injector (AFI).
Microprocessor
An integrated circuit in a microcomputer that controls information flow.
Nitrogen Oxides (NO
x
)
Nitrogen oxides Form by a reaction between nitrogen and oxygen at high temperatures and pressures
in the combustion chamber.
Normally closed
Refers to a switch that remains closed when no control force is acting on it.
Normally open
Refers to a switch that remains open when no control force is acting on it.
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