Glossary of Electronic Control Terms

TM 9-2320-312-24-2

Systems Operation Section

American Wire Gauge (AWG) AWG is a measure

The engine has built-in diagnostics in order to

of the diameter of electrical wire. AWG is also

ensure that all of the components are operating

a measure of the current carrying capacity of

properly. In the event of a system component

electrical wire. When the AWG number is smaller,

failure, the operator will be alerted to the condition

the diameter of the wire is larger. When the AWG

via the check engine light that is located on the

number is larger, the diameter of the wire is smaller.

dashboard. An electronic service tool can be used

to read the numerical code of the faulty component

Atmospheric Pressure Sensor The atmospheric

or condition. Also, the cruise control switches can

pressure sensor measures barometric pressure. The

be used to flash the code on the check engine light.

sensor sends a signal to the ECM. The signal is

Intermittent faults are logged and stored in memory.

used in engine control and in engine operation.

Starting The Engine

Before Top Center (BTC) BTC is the 180 degrees

of crankshaft rotation before the piston reaches

The engine's ECM will automatically provide the

the top center position in the normal direction of

correct amount of fuel in order to start the engine.

rotation.

Do not hold the throttle down while the engine

is cranking. If the engine fails to start in twenty

Boost Pressure Sensor The boost pressure sensor

seconds, release the starting switch. Allow the

measures inlet manifold air pressure. The boost

starting motor to cool for two minutes before the

pressure sensor sends a signal to the ECM.

starting motor is used again.

Bypass Circuit A bypass circuit is a circuit that is

NOTICE

used as a substitute circuit for an existing circuit. A

Excessive ether (starting fluid) can cause piston and

bypass circuit is typically used as a test circuit.

ring damage. Use ether for cold weather starting pur-

poses only.

Calibration Calibration is an electronic adjustment

of a sensor signal.

Cold Mode Operation

Coolant Temperature Sensor The coolant

temperature sensor measures the engine coolant

Starting the engine and operation in cold weather is

temperature. The sensor sends a signal to the ECM.

dependent on the type of fuel that is used, the oil

The engine's coolant temperature is used in Cold

viscosity, and other optional starting aids. For more

Mode operation. Coolant temperature is also used

information, refer to the Operation and Maintenance

in order to optimize engine performance.

Manual, "Cold Weather Operation" topic (Operation

Section).

Cruise Control Range The cruise control range

establishes the vehicle speed range for the

operation of cruise control. The range is usually

i01564336

limited to the speed range that is anticipated on

Glossary of Electronic Control

the open road.

Terms

Code See the Diagnostic Code.

SMCS Code: 1900

Customer Specified Parameters A customer

specified parameter is a parameter that can be

Accelerator Pedal Position Sensor The accelerator

changed. A customer specified parameter's value

pedal position sensor is an electronic sensor

is set by the customer. These parameters are

that is connected to the accelerator pedal. The

protected by customer passwords.

accelerator pedal position sensor sends a Pulse

Width Modulated Signal to the ECM.

CAT Data Link The data link is an electrical

connection that is used to communicate with other

After Market Device An after market device is

microprocessor based devices. The microprocessor

a device or an accessory that is installed by the

based devices are compatible with the proposed

customer after the vehicle is delivered.

American Trucking Association and the SAE

Standard. These devices include trip recorders,

Air-To-Air Aftercooler An air-to-air aftercooler is

electronic dashboards, and maintenance systems.

a device that is used on turbocharged engines

The data link is also the communication medium that

in order to cool inlet air that has undergone

is used for programming with the electronic service

compression. The inlet air is cooled after the inlet

tool. The data link is also used for troubleshooting

air passes through the turbocharger. The inlet air

with the electronic service tool.

is passed through an aftercooler (heat exchanger)

that uses ambient air for cooling. The inlet air that

has been cooled advances to the inlet manifold.