3408 AND 3412 INDUSTRIAL ENGINE OIL WELL SERVICE Caterpillar

Glossary Of Terms

Usage:

Actual Rack

The ECM interpretation of the signal from the Rack Position Sensor which represents actual position of the rack, assuming the sensor signal is valid. If the rack controls are working properly, Actual Rack should follow Desired Rack.

After Market Device

A device or accessory installed by the customer after the engine is delivered.

American Wire Gauge (AWG)

A measure of the diameter (and therefore the current carrying ability) of electrical wire. The smaller the AWG number, the larger the wire.

Atmospheric Pressure Sensor

This sensor measures crankcase pressure and sends a signal to the ECM.

Boost Pressure Sensor

This sensor measures inlet manifold air pressure and sends a signal to the ECM.

Breakout T

A test harness designed to permit normal circuit operation while measuring voltages, typically inserted between the two ends of a connector.

Brushless Torque Motor (BTM)

Solenoid used to move fuel rack servo spool valve and timing advance spool valve.

Bypass Circuit

A circuit, usually temporary, to substitute for an existing circuit, typically for test purposes.

Calibration

As used here, is an electronic adjustment of a sensor signal.

Check Engine Lamp

Sometimes referred to as the Diagnostic Lamp, it is used to warn the operator of the presence of an active diagnostic code. Some installations may have both.

Component Identifier (CID)

Two or three digit diagnostic code which is assigned to each component.

Coolant Level Sensor

The coolant level sensor operates as a coolant loss sensor indicating the presence/absence of coolant at the sensor probe tip.

Coolant Temperature Sensor

The coolant temperature sensor measures the temperature of the engine coolant. The ECM uses this information to set the mode of operation and to notify the operator of excessive engine temperature if the engine protection mode is not OFF.

Customer Specified Parameter

A parameter that can be changed and whose value is set by the customer. Protected by Customer Passwords.

Data Link

A twisted two wire electrical connection for communication with other microprocessor based devices that are compatible with the American Trucking Association (ATA) and SAE Standard such as trip recorders, electronic dashboards, and maintenance systems. The Data Link is also the communication medium used for programming and troubleshooting with Caterpillar devices.

Desired Rack Position (Des Rack Pos on ECAP)

The rack position where the ECM wants to move the rack, based on the ECM trying to maintain Desired Speed (rpm). Desired Rack will not proceed beyond the FRC Rack or Rated Rack.

Desired Engine rpm

An input to the electronic governor within the ECM. The electronic governor uses inputs from the Throttle Position Sensor, Synchronization Status and Customer Parameters to determine Desired rpm.

Diagnostic Code

It is an indication of a problem or event in the ECM or electronic system.

Diagnostic Lamp

Sometimes referred to as the Check Engine Light, it is used to warn the operator of the presence of an active diagnostic code.

Duty Cycle

Refer to Pulse Width Modulation.

Electronic Control Analyzer Programmer (ECAP)

A Caterpillar Electronic Service Tool used for programming and diagnosing a variety of electronic controls.

Electronic Control Module (ECM)

The engine control computer that provides power to the electronics, monitors sensor inputs and acts as a governor to control engine rpm.

Engine Speed (rpm) Sensor

A magnetic sensor that measures engine rpm from the rotation of the flywheel.

Failure Mode Identifier (FMI)

Type of failure the component experienced (adopted from SAE standard practice J1587 diagnostics).

Fuel Ratio Control (FRC) Rack Position

FRC Fuel Position is a limit based on control of the fuel-to-air ratio and is used for emission control purposes. When the ECM senses a higher boost pressure (more air into cylinder), it increases the FRC Fuel Pos limit (allows more fuel into cylinder).

Fuel OFF and Fuel ON

Refers to minimum fuel and maximum fuel positions of the fuel rack.

Harness

The wiring bundle connecting all components of the Electronic System.

Hertz (Hz)

Measure of frequency in cycles per second.

Oil Pressure Sensor

This sensor measure engine oil pressure and sends a signal to the ECM.

Open Circuit

Condition where an electrical wire or connection is broken, so that the signal or the supply voltage can no longer reach its intended destination.

Parameter

A programmable value which affects the characteristics or behavior of the engine.

Password

A group of numeric or alpha-numeric characters, designed to restrict access to parameters. The ECM System requires correct passwords in order to change Customer Specified Parameters (Customer Passwords) or certain engine specifications (Factory Passwords). Passwords are also required to clear certain diagnostic codes.

Personality Module or Ratings Personality Module

The small blue module inserted into the ECM which contains all the instruction (software) for the ECM and performance maps for a specific power family.

Pulse Width Modulation (PWM)

A signal consisting of variable width pulses at fixed intervals, whose TIME ON versus TIME OFF can be varied (also referred to as duty cycle).

Example of Pulse Width Modulation Signals

Throttle vs. Duty Cycle Relationship

Rack Position Sensor

A linear position sensor which follows movement of the rack assembly and sends an electrical signal to the ECM.

Rack Solenoid (BTM)

A rotary proportional solenoid (also called a BTM) used to move the fuel rack servo spool valve.

Rated Rack Position

A limit on rack position which provides the specified power and torque curves. This value comes from maps programmed into the personality module at the factory.

Reference Voltage

A regulated voltage supplied by the ECM to a sensor. The reference voltage is used by the sensor to generate a signal voltage.

Sensor

A device used to detect and convert a change in pressure, temperature, or mechanical movement into an electrical signal.

Service Program Module (SPM)

A software program on a factory programmable computer chip, designed to adapt an ECAP to a specific application.

Short Circuit

A condition where an electrical circuit is unintentionally connected to an undesirable point. Example: a wire which rubs against an engine frame until it wears off its insulation and makes electrical contact with the frame.

Signal

A voltage or waveform used to transmit information typically from a sensor to the ECM.

Speed burp

A sudden brief change in engine rpm.

Speed Sensor Magnetic Pickup (SSMPU)

Speed sensor magnetic pickup (SSMPU) is used to sense and send a signal to the ECM to determine engine rpm.

Subsystem

As used here, it is a part of the ECM System that relates to a particular function, for instance: throttle subsystem, etc.

Supply Voltage

A constant voltage supplied to a component to provide electrical power for its operation. It may be generated by the ECM, or it may be battery voltage supplied by the engine wiring.

Throttle Position