Automotive terms Modern M

Automotive Technical terms and abbreviations overview used in the industry, Guide and explanations.

The following are examples of Mid Modern technical terms recommended for general use worldwide. For in-depth specific terms also see terms for historic vintage and specific areas such as Paint.

MAGNET:
Any body with the property of attracting iron or steel.

MAGNETIC FIELD:
The area surrounding the poles of a magnet that is affected by its attraction or repulsion forces.

MAIN LINE PRESSURE:
Often called control pressure or line pressure, it refers to the pressure of the oil leaving the pump and is controlled by the pressure regulator valve.

MALFUNCTION INDICATOR LAMP (MIL):
Previously known as a check engine light, the dash-mounted MIL illuminates and signals the driver that an emission or driveability problem with the powertrain has been detected by the ECM/PCM. When this occurs, at least one diagnostic trouble code (DTC) has been stored into the control module memory.

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR:
Reads the amount of air pressure (vacuum) in the engine's intake manifold system; its signal is used to analyze engine load conditions.

MANIFOLD VACUUM:
Low pressure in an engine intake manifold formed just below the throttle plates. Manifold vacuum is highest at idle and drops under acceleration.

MANIFOLD:
A casting of passages or set of pipes which connect the cylinders to an inlet or outlet source.

MANUAL LEVER POSITION SWITCH (MLPS):
A mechanical switching unit that is typically mounted externally to the transmission/transaxle to inform the PCM/ECM which gear range the driver has selected.

MANUAL VALVE:
Located inside the transmission/transaxle, it is directly connected to the driver's shift lever. The position of the manual valve determines which hydraulic circuits will be charged with oil pressure and the operating mode of the transmission.

MANUMATIC
modern tearm of automatic transmission that allows the driver to also select gears, paddle-shifters or buttons.

MANUAL VALVE LEVER POSITION SENSOR (MVLPS):
The input from this device tells the TCM what gear range was selected. MASS AIR FLOW (MAF) SENSOR: Measures the airflow into the engine.

MARQUE
A brand for a Automotive manufacturer often there logos and trademark.

MASTER CYLINDER:
The primary fluid pressurizing device in a hydraulic system. In automotive use, it is found in brake and hydraulic
clutch systems and is pedal activated, either directly or, in a power brake system, through the power booster.

MacPherson STRUT:
A suspension component combining a shock absorber and spring in one unit.

MEDIUM THROTTLE:
Approximately one-half of accelerator pedal travel.

MEGA:
A metric prefix indicating one million.

MEMBER:
An independent component of a hydrodynamic unit such as an impeller, a stator, or a turbine. It may have one or more elements.

MERCON:
A fluid developed by Ford Motor Company in 1988. It contains a friction modifier and closely resembles operating characteristics of Dexron

METAL SEALING RINGS:
Made from cast iron or aluminum, their prirnary application js with dynamic components involving pressure sealing
circuits of rotating members, These rings are designed with either butt or hook lock end joints.

METER (ANALOG):
A linear-style meter representing data as lengths; a needle-style instrument interfacing with logical numerical increments. This style of electrical meter uses relatively low impedance internal resistance and cannot be used for testing electronic circuitry.

METER (DIGITAL):
Uses numbers as a direct readout to show values. Most meters of this style use high impedance internal resistance and must be used for testing low current electronic circuitry.

MICRO:
A metric prefix indicating one-millionth (0.000001).

MILLI:
A metric prefix indicating one-thousandth (0.001)

MINIMUM THROTTLE:
The least amount of throttle opening required for upshift; normally close to zero throttle.

MISFIRE:
Condition occurring when the fuel mixture in a cylinder fails to ignite, causing the engine to run roughly.

MODULE:
Electronic control unit, amplifier or igniter of solid state or integrated design which controls the current flow in the ignition primary circuit based on input from the pick-up coil. When the module opens the primary circuit, high secondary voltage is induced in the coil.

MODULATED:
In an electronic-hydraulic converter clutch system (or shift valve system), the term modulated refers to the pulsing of a solenoid, at a variable rate. This action controls the buildup of oil pressure in the hydraulic circuit to allow a controlled amount of clutch slippage.

MODULATED CONVERTER CLUTCH CONTROL (Mccc):
A pulse width duty cycle valve that controls the converter lockup apply pressure and maximizes smoother transitions between lock and unlock conditions.

MODULATOR PRESSURE (THROTTLE PRESSURE):
A hydraulic signal oil pressure relating to the amount of engine load, based on either the amount of throttle plate opening or engine vacuum.

MODULATOR VALVE:
A regulator valve that is controlled by engine vacuum, providing a hydraulic pressure that varies in relation to engine torque. The hydraulic torque signal functions to delay the shift pattern and provide a line pressure boost. (See throttle valve.)

MOTOR:
An electromagnetic device used to convert electrical energy into mechanical energy.

MUFFLER
Exhaust or silencer of an internal combustion engine

MULTIPLE-DISC CLUTCH:
A grouping of steel and friction lined plates that, when compressed together by hydraulic pressure acting upon a
piston, lock or unlock a planetary member.

MULTI-WEIGHT:
Type of oil that provides adequate lubrication at both high and low temperatures. needed to move one amp through a resistance of one ohm.

MUSHY:
Same as soft; slow and drawn out clutch apply with very little shift feel.

MUTUAL INDUCTION:
The generation of current from one wire circuit to another by movement of the magnetic field surrounding a current-carrying circuit as its ampere flow increases or decreases.

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