Glossary -807640192

TM 9-2320-312-24-2

Troubleshooting Section

Passwords

Active Diagnostic Code An active diagnostic code

describes a condition that is currently present in

order to alert the driver or the service technician of

System configuration parameters are protected

an abnormal parameter of engine operation. Refer

by factory passwords. Factory passwords are

to a Diagnostic Fault Code.

calculated on a computer system that is available

only to Caterpillar dealers. Since factory passwords

Aftermarket Device An aftermarket device is a

contain alphabetic characters, only the electronic

device or an accessory that is installed by the

service tool may change system configuration

customer after the vehicle is delivered.

parameters. System configuration parameters affect

the power rating family or emissions.

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

a device that is used on turbocharged engines

Customer parameters are protected by customer

in order to cool inlet air that has undergone

passwords. The customer passwords are

compression. The inlet air is cooled after the inlet

programmed by the customer. Factory passwords

air passes through the turbocharger. The inlet air

can be used to change customer passwords if

is passed through an aftercooler (heat exchanger)

customer passwords are lost.

that uses ambient air for cooling. The inlet air that

has been cooled advances to the inlet manifold.

Refer to Troubleshooting, "Customer Passwords"

and Troubleshooting, "Factory Passwords".

Alternating Current (AC) Alternating current is an

electric current that reverses direction at a regular

i01632525

interval that is reoccurring.

Glossary

American Wire Gauge (AWG) AWG is a measure

of the diameter of electrical wire. AWG is also

SMCS Code: 1000

a measure of the current carrying capacity of

electrical wire. When the AWG number is smaller,

A/C High Pressure Switch The a/c high pressure

the diameter of the wire is larger. When the AWG

switch senses refrigerant pressure in the air

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

conditioning system. The a/c high pressure switch

opens the electrical contacts and/or the a/c high

Anti-Lock Brake System (ABS) An ABS is a brake

pressure switch closes the electrical contacts. The

system that attempts to reduce a skid during brake

opening and/or closing of the electrical contacts

operation. A power train electronic control can turn

depends on the pressure in the system in order

off the engine retarder, if necessary. Also, a power

to turn on the cooling fan. This switch may be

train electronic control can signal the engine ECM

connected to the ECM or this switch may not be

to deactivate the engine retarder.

connected to the ECM.

Atmospheric Pressure Sensor The atmospheric

ATA Data Link (American Trucking Association)

pressure sensor measures barometric pressure. The

The ATA data link is a two wire electrical connection

sensor sends a signal to the ECM. The signal is

for communication with other microprocessor based

used in engine control and in engine operation.

devices that are compatible with the American

Trucking Association standards and SAE standards

Auxiliary Retarder Relay The brakes' solenoids

(J1587 and J1708 ) such as trip recorders,

are driven by an OEM installed relay, which is driven

electronic dashboards, power train controls, and

by the ECM.

maintenance systems. The data link is also the

serial communication medium that is used for

Before Top Center (BTC) BTC is the 180 degrees

programming and troubleshooting with Caterpillar

of crankshaft rotation before the piston reaches

devices.

the top center position in the normal direction of

rotation.

Accelerator Pedal Position The accelerator pedal

position is the interpretation by the ECM of the

Boost Pressure Sensor The boost pressure sensor

signal from the accelerator pedal position sensor.

measures inlet manifold air pressure. The boost

pressure sensor sends a signal to the ECM.

Accelerator Pedal Position Sensor The accelerator

pedal position sensor is an electronic sensor

Bypass Circuit A bypass circuit is a circuit that is

that is connected to the accelerator pedal. The

used as a substitute circuit for an existing circuit. A

accelerator pedal position sensor sends a pulse

bypass circuit is typically used as a test circuit.

width modulated signal to the ECM.

Calibration Calibration is an electronic adjustment

of a sensor signal.