3406C (PEEC III) DIESEL TRUCK ENGINE Caterpillar

6.0 Glossary Of PEEC III Terms

Usage:

Actual Rack: The ECM's 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".
Actual Timing Advance: Degrees of advance beyond static, as measured by the Timing Position Sensor (assumes that Timing Position Sensor is calibrated).
After Market Device: A device or accessory installed by the customer after the vehicle is delivered.
Air-To-Air Aftercooler (ATAAC): A means of cooling intake air after the turbocharger, using ambient air for cooling. The intake air is passed through an aftercooler (heat exchanger) mounted in front of the radiator before going to the intake manifold.
Alternating Current (AC): The direction of current flow changes (alternates) regularly and constantly.
American Wire Gauge (AWG): A measure of the diameter (and therefor the current carrying ability) of electrical wire. The smaller the AWG number, the larger the wire.
Before Top Dead Center (BTDC) or Before Top Center (BTC): The 180° of crankshaft rotation before the piston reaches Top Dead Center (normal direction of rotation).
Boost Pressure Sensor: This sensor measures inlet manifold air pressure and sends a signal to the ECM.
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.
Coolant Level Sensor: The coolant level sensor is a vehicle OEM purchased and installed component. The 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.
Cruise Control Range: The range that the cruise control can operate within. Usually limited to the speed range anticipated on the open road.
Code: See Diagnostic Code.
Customer Specified Parameter: A Parameter that can be changed and whose value is set by the customer. Protected by Customer Passwords.
Data Link: An electrical connection for communication with other microprocessor based devices that are compatible with the American Trucking Association 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 PEEC III governor trying to maintain "Desired RPM". "Desired Rack" will not go farther than the "FRC Rack" or "Rated Rack".
Desired RPM: An input to the electronic governor within the ECM. The electronic governor uses inputs from the Throttle Position Sensor, Engine Speed Sensor, Cruise Control, and Customer Parameters to determine "Desired RPM".
Desired Timing Advance ("Des Timing Adv" on ECAP): The injection timing advance calculated by the ECM as required to meet emission and performance specifications.
Diagnostic Code: Sometimes referred to as a "fault code", it is an indication of a problem or event in the PEEC III 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.
Digital Diagnostic Tool (DDT): A Caterpillar electronic service tool used for programming and for diagnosing the 3406 PEEC III system.
Direct Current: The type of current where the only direction of current flow is consistently in one direction only.
Duty Cycle: Same as 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 PEEC III electronics, monitors PEEC III inputs and acts as a governor to control engine rpm.
Engine Speed Sensor: A magnetic sensor that uses engine speed from the rotation of the fuel injection pump camshaft (slotted retainer).
Estimated Dynamic Timing: The ECM's estimation of actual injection timing calculated internally by the ECM. Est. Dyn Timing = Static Timing Spec + Actual Timing Advance + Port Effect (.2 deg/100rpm).
Failure Mode Identifier (FMI): Type of failure the component experienced (adopted from SAE standard practice J1587 diagnostics).
Fuel Ratio Control (FRC) Rack: FRC Fuel Pos. - is a limit based on control of the fuel-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 PEEC III 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.
Original Equipment Manufacturer (OEM): As used here, the manufacturer of a vehicle in which a Caterpillar engine is installed.
Parameter: A programmable value which affects the characteristics or behavior of the engine and/or vehicle.
Password: A group of numeric or alpha-numeric characters, designed to restrict access to parameters. The PEEC III 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 horsepower family.
Parameter Identifier (PID): Two or three digit code which is assigned to each component.
Programmable Electronic Engine Control (PEEC): The complete electronic system that monitors and controls engine operation under all conditions.
Progressive Shifting: Shifting up through the lower gears quickly by not winding up the engine in each gear. Shifts are made above peak torque but below rated rpm. Needlessly winding up the engine into the higher rpm ranges before shifting to the next gear wastes fuel and fails to take advantage of the torque rise of the engine. The two steps (LoGr1, LoGr2) approximate ideal progressive shifting. Low gear #1 is typically set no lower than peak torque plus 200 rpm. Low gear #2 is typically set midway between Low gear #1 rpm limit and Top Engine Limit.
Power Take Off (PTO): Operated with the cruise control switches, this mode permits setting a constant engine rpm when the vehicle is not moving (like a manual throttle control cable).
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
Rated Rack Position: A limit on rack position which provides the specified horsepower and torque curves. this value comes from maps programmed into the personality module at the factory.
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.
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.
Retarder Enable Signal: The Retarder Enable signal is provided by the ECM to indicate that conditions are acceptable for an engine retarder to operate. Operation of the retarder is inhibited during undesirable engine operating conditions (such as while the engine is being fueled).
Sensor: A device used to detect and convert a change in pressure, temperature, or mechanical movement into an electrical signal.
Service Program Module: A software program on a factory programmable computer chip, designed to adapt an ECAP or DDT 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 a vehicle 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 speed.
Static Timing Specification: Fixed number of degrees determined by design of the fuel pump camshaft (determines injection timing with no advance). Note that the value displayed is the specification for static timing, not an electrically measured value.
Subsystem: As used here, it is a part of the PEEC III 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.
"T" Harness: A test harness designed to permit normal circuit operation while measuring voltages, typically inserted between the two ends of a connector.
Throttle Position: The ECM's interpretation of the signal from the Throttle Position Sensor.
Throttle Position Sensor: An electronic sensor which is connected to the accelerator pedal and sends a Pulse Width Modulated signal to the ECM.
Timing Position Sensor: A linear position sensor which follows movement of the timing advance unit and sends an electrical signal to the ECM.
Timing Solenoid (BTM): A rotary proportional solenoid (also called a BTM) used to move the timing advance unit spool valve.
Total Tattletale: Total number of changes to all Customer Specified Parameters.
Transducer: A device which converts a mechanical signal to an electrical signal.
Transducer Module: A sealed unit mounted below the rack actuator housing and contains the engine oil pressure sensor, boost pressure sensor, and protective signal conditioning circuitry.
Vehicle Speed Buffer: A device used to condition and amplify the output of the vehicle speed sensor.
Vehicle Speed Sensor: An electro-magnetic pickup that measures vehicle speed from the rotation of gear teeth in the drive train of the vehicle.