3512 INDUSTRIAL ENGINE OIL WELL SERVICE Caterpillar

Section 6: Glossary Of Terms

Usage:

Actual Rack: The ECM interpretation of the signal from the Rack Position Sensor. If the rack controls are working, Actual Rack should follow Desired Rack.
Aftermarket 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.
Analog Sensors: Analog Sensors produce a DC output signal that can vary typically from +0.2 to +4.8 VDC. The sensors are used to detect and convert a change in temperature or pressure into an electrical signal.
Analog Sensor Supply: The +5 VDC and +8 VDC supply from the ECM is used to power certain analog sensors. Refer to P-521: Sensor Supply Voltage.
Analog Return: The common line (ground) for the Analog Sensor supply from the ECM used to power the analog sensors.
Atmospheric (Turbocharger Inlet) Pressure Sensor: This sensor measures air pressure after the air filter and sends a signal to the Electronic Control Module (ECM).
Before Top Center (BTC): The 180 degrees of crankshaft rotation before the piston reaches the very top of its travel during the compression stroke (normal direction of rotation).
Breakout T: A test harness designed to allow normal circuit operation while measuring circuit voltages. Typically inserted between a mated connector.
Bypass Circuit or Harness: A circuit (usually temporary) used as a substitute for an existing circuit, typically for test purposes.
Calibration: As used here, is an electronic adjustment of a sensor signal.
CAT Data Link: A two wire electrical connection for communication with other microprocessor based devices such as the electronic monitoring system. The CAT data link is also the serial communication medium used for programming and troubleshooting with Caterpillar Electronic Service Tools.
Code: Refer to Diagnostic Code.
Cold Mode: A mode of engine operation where the timing is retarded and the low idle may be raised for engine protection, reduced smoke emissions and faster warm up time.
Component IDentifier (CID): A number which represents each component in the electronic control system. Refer to Section 4: Diagnostic Terminology in this manual.
Communication Adapter Tool: The Communication Adapter Tool provides a communication link between the ECM and the Electronic Service Tool.
Coolant Temperature Sensor: This analog sensor measures jacket water temperature and sends a signal to the Electronic Control Module (ECM).
Desired RPM: An input to the electronic governor control within the ECM. The electronic governor uses inputs from the Throttle Position Sensor and Speed/Timing Sensor to determine Desired RPM.
Diagnostic Code: An indication of a problem or event in the electronic system.
Digital Sensors: Digital Sensors produce a Pulse Width Modulation of Duty Cycle type of signal. An example would be the Throttle Position Sensor.
DT, DT Connector, Deutsch DT: A type of connector manufactured by Deutsch that is used on Caterpillar engines.
Duty Cycle: Refer to Pulse Width Modulation.
Electronic Control Analyzer Programmer (ECAP): A Caterpillar Electronic Service Tool developed by Caterpillar for programming and diagnosing a variety of Caterpillar electronic controls using the RS-232 data link.
Electronic Control Module (ECM): The engine control computer that provides power to the electronic system, monitors sensors and component inputs, and acts as a governor to control injection timing and the engine rpm.
Electronic Engine Control: The complete electronic system that monitors and controls engine operation under all conditions.
Electronic Technician (ET): A software program that runs on a personal computer (PC). Similar in function to the ECAP.
Ether Relay: Relay used to actuate the ether injection system. The relay is controlled by the Electronic Control Module (ECM).
Failure Mode Identifier (FMI): A number representing the type of failure a component experienced (adopted from SAE standard practice J1587 diagnostics). Refer to Section 4: Diagnostic Terminology.
Fuel Position: An internal signal within the ECM, from the Electronic Governor to Fuel Injection Control. It is based on Desired RPM, FRC Fuel Position, Rated Fuel Position and engine rpm. Refer to Section 1: System Overview.
Fuel Ratio Control (FRC): FRC Fuel Pos is a limit based on control of the fuel to air ratio that is used for emission control purposes. When the ECM senses a higher Inlet Manifold (Boost) Pressure (more air into cylinder), it increases the FRC Fuel Pos limit (allows more fuel into cylinder).
Full Load Setting (FLS): Number representing fuel system adjustment made at the factory to fine tune the fuel system. Correct value for this parameter is stamped on the engine information plate.
Full Torque Setting (FTS): Similar to Full Load Setting.
Harness: The wiring bundle (loom) connecting all components of the Electronic System.
Hertz (Hz): Measure of frequency in cycles per second.
Logged Diagnostic Codes: Describes codes which are stored in memory. They can be an indicator of possible causes of intermittent problems.
Oil Pressure Sensor: This analog sensor measures engine oil pressure and sends a signal to the Electronic Control Module (ECM).
Open Circuit: Condition where an electrical wire or connection is broken, that prevents the signal or the supply voltage from reaching its intended destination.
Parameter: A programmable value or limit which determines the characteristics or behavior of the engine.
Password: A group of numeric or alphanumeric characters, designed to restrict access to parameters. The electronic system requires correct passwords in order to change certain engine specifications (Factory Passwords). Passwords are also required to clear certain diagnostic codes.
Personality Module or Ratings Personality Module: The module attached inside of the ECM which contains all the instructions (software) for the ECM and performance maps for a specific application.
Power Cycled: Applying power, removing power, and reapplying power again to the Electronic Control Module (ECM). Refers to cycling the Engine Control Switch from any position to the OFF position and back to the START/RUN position.
Powered Down: Removing power from the Electronic Control Module (ECM). Refers to cycling the Engine Control Switch from any position to the OFF/RESET position.
Powered Up: Applying power to the Electronic Control Module (ECM). Refers to cycling the Engine Control Switch from the OFF/RESET position to the START position.
Pulse Width Modulation (PWM): A signal consisting of variable width pulses at fixed intervals, whose ratio of TIME ON versus total TIME OFF can be varied (also referred to as duty cycle).

Example of Pulse Width Modulation (PWM) Signals
Rated Fuel Limit: Indicates the maximum allowable fuel position (longest injector pulse). It will produce rated power for this engine configuration.
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 designed to adapt an Electronic Service Tool 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 the engine 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.
Static Timing: The basis for correct fuel injection timing and valve mechanism operation, as determined by the Timing Reference Ring and alignment of the rear gear group. Also referred to as Base Timing.
Subsystem: As used here, it is a part of the Electronic 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 vehicle battery voltage supplied by the vehicle wiring.
Throttle Position: The ECM interpretation of the signal from the Throttle Position Sensor.
Throttle Position Sensor: An electronic sensor which is connected to an accelerator pedal or a hand lever and sends a Pulse Width Modulated Signal to the ECM.
Timing Calibration Sensor: A magnetic pickup installed in the Top Center (TC) port. This sensor is used by the ECM to perform a timing calibration.
Top Center (TC): A reference to crankshaft position when the piston has reached the very top of its rotation during the compression stroke.
Total Tattletale: Total number of changes to all Programmable Parameters stored in the ECM.
Turbocharger Inlet Pressure Sensor: This analog sensor measures the turbocharger compressor inlet air pressure and sends a signal to the ECM.