After Market Device - The customer or the machine (OEM) installs these devices or accessories. This installation is completed after the engine is delivered.
Alternating Current (AC) - The direction of current flow changes. The current flow alternates constantly.
American Wire Gauge (AWG) - This is the measurement of the diameter of electrical wire. This is also the measurement of the ability of electrical wire to carry current. A smaller AWG number reflects a larger wire.
Before Top Center (BTC) - BTC is the 180 degrees of crankshaft rotation before the piston reaches Top Center in the normal direction of rotation.
Boost Pressure Sensor - This sensor measures inlet manifold air pressure. The sensor sends the signal to the ECM.
Brushless Torque Motor (BTM) - This solenoid moves the fuel rack servo spool valve. This is also called rack solenoid.
Bypass Circuit - This circuit substitutes an existing circuit. The circuit is usually a temporary circuit. The circuit is used for testing.
Calibration - Calibration is an electronic adjustment of a sensor signal.
CAT Data Link - The data link is an electrical connection that is used to communicate with other microprocessor based devices. The microprocessor based devices are compatible with the proposed American Trucking Association and the SAE Standard. These devices include trip recorders, electronic dashboards, and maintenance systems. The data link is also the communication medium that is used for programming with the electronic service tool. The data link is also used for troubleshooting with the electronic service tool.
Code - See Diagnostic Code.
Desired Rack Position (DES Rack Pos on ECAP) - The ECM calculates this rack setting. This is needed to attain or maintain the desired RPM.
Desired RPM - The desired RPM is input to the electronic governor within the ECM. The electronic governor uses inputs from the Throttle Position Sensor, the Speed Timing Sensor and the Customer Parameters in order to determine the desired RPM.
Desired Timing Advance (DES Timing ADV on ECAP) - The fuel injection timing advance is calculated by the ECM. The calculation is used to meet emission and performance specifications.
Diagnostic Code - A diagnostic code is an indication of a problem or event in the electronic system.
Direct Current (DC) - Direct current is the type of current that flows consistently in only one direction.
Duty Cycle - See Pulse Width Modulation.
Electrically Erasable Programmable Read Only Memory (EEPROM) - The EEPROM is a large scale integrated circuit chip for storing digital data. This chip can be electronically erased and reprogrammed. This is used to store electronic engine control parameters that can be changed using the ECAP.
Electronic Control Analyzer And Programmer (ECAP) - The ECAP is a Caterpillar electronic service tool. The ECAP is used for programming and for diagnosing various types of electronic controls.
Electronic Control Module (ECM) - The ECM is the engine's control computer. The ECM provides power to the electronics for the system. The ECM monitors the information that is input by the system. The ECM acts as a governor in order to control engine rpm.
Electronic Control System - This is the complete electronic system. This system monitors and controls the engine operation under all conditions.
Engine Speed Sensor - This magnetic sensor measures the engine speed. The engine speed is measured from the rotation of the fuel injection pump camshaft (slotted retainer).
Estimated Dynamic Timing - This is the estimated calculation of actual injection timing by the ECM. Est Dyn Timing = Static Timing Spec + Actual Timing Advance + Port Effect (.2 deg/100 rpm).
Fuel Ratio Control (FRC) - The FRC is a limit that is based on the control of the fuel to air ratio. The FRC is used for emission control. When the ECM senses a higher turbocharger outlet pressure, the ECM increases the limit for the FRC in order to allow more fuel into the cylinders.
Fuel Off and Fuel On - This refers to the minimum fuel and the maximum fuel positions of the fuel rack.
Harness - The harness is the bundle of wiring that connects all the components of the electrical engine system.
Hertz (Hz) - Hertz is the measure of frequency in cycles per second.
Inlet Air Pressure Sensor - This sensor measures the inlet air pressure. The sensor sends a signal to the Electronic Control Module (ECM).
Jacket Water Aftercooler (JWAC) - This is a method of cooling inlet air after the turbocharger. This method uses jacket water for cooling. The inlet air is passed through an aftercooler (heat exchanger) before going to the inlet manifold.
Oil Pressure Sensor - This sensor measures engine oil pressure. The sensor sends a signal to the ECM.
Open Circuit - An open circuit is a broken electrical wire connection. The signal or the supply voltage cannot reach the intended destination.
Original Equipment Manufacturer (OEM) - The equipment manufactured by an OEM that has a Caterpillar engine for power.
Parameter - A parameter is a programmable value which affects the characteristics or the behavior of the engine and/or machine.
Password - A password is a group of numeric characters or alphanumeric characters. A password is designed to restrict access to parameters. The Electronic Control system requires correct passwords in order to change Customer Specified Parameters (Customer Passwords). Factory passwords are also required in order to change certain engine specifications. Passwords are also required to clear certain diagnostic codes.
Personality Module Or Ratings Personality Module - A personality module refers to the software that is downloaded onto the small, blue module. The module is inserted into the ECM. The module contains all the instructions (software) for the ECM and performance maps for a specific horsepower family.
Programmable Read Only Memory (PROM) - A large scale integrated circuit chip. This chip stores digital data. The chip can only be programmed at the factory. This chip is used in the personality module. The chip stores the control logic and stores the rating information.
Pulse Width Modulation (PWM) - A PWM is a digital type of electronic signal that corresponds to a measured variable. The length of the pulse (signal) is controlled by the measured variable. The variable is quantified by a certain ratio. This ratio is the percent of "TIME-ON" that is divided by the percent of "TIME-OFF".
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| Illustration 1 | g00350656 |
Example of pluse width modulation | |
Rated Rack Position - This is a limit on the rack position. This provides the specified horsepower and torque curves. This value comes from maps that have been programmed into the personality module at the factory.
Rack Position Sensor - A linear position sensor which follows the movement of the rack assembly. This sensor sends an electrical signal to the ECM.
Rack Solenoid (BTM) - A rotary proportional solenoid used to move the fuel rack servo spool valve. This is also called a Brushless Torque Motor (BTM).
Reference Voltage - The regulated voltage supplied by the ECM to a sensor. The reference voltage is used by the sensor to generate a signal voltage.
Sensor - A sensor is used to detect a change in the pressure, in the temperature, or in mechanical movement. When any of these changes are detected, a sensor converts the change into an electrical signal.
Service Program Module (SPM) - This module is a software program. This module is part of a computer chip that is programmed at the factory. The module is designed to adapt an ECAP to a specific application.
Short Circuit - A short circuit is an electrical circuit that is mistakenly connected to an undesirable point. For example, an electrical contact is made with the frame whenever an exposed wire rubs against a truck's frame.
Signal - A signal is a voltage or a wave that is used to transmit information that is typically from a sensor to the ECM.
Speed Burp - A speed burp is a sudden brief change in engine speed.
Static Timing Specification - The fixed number of degrees determined by the design of the fuel pump camshaft. This will determine the injection timing with no advance. The value displayed is the specification for static timing and is NOT an electrically measure value.
Subsystem - A subsystem is part of the EUI system that relates to a particular function.
Supply Voltage - Supply voltage is a constant voltage that is supplied to a component in order to provide electrical power for operation. Supply voltage may be generated by the ECM. Supply voltage may also be the battery voltage that is supplied by the wiring harness.
"T" Harness - This harness is a test harness that is designed to permit normal circuit operation and the measurement of the voltage simultaneously. Typically, the harness is inserted between the two ends of a connector.
Throttle Position - The throttle position is the ECM interpretation of the signal from the Throttle Position Sensor.
Throttle Position Sensor - This is an electronic sensor connected to the throttle control. The sensor sends a Pulse Width Modulated Signal to the ECM.
Total Tattletale - The total tattletale is the total number of changes to all system parameters.
Transducer - A device which converts a mechanical signal to an electrical signal.
Transducer Module - This is a sealed unit mounted below the rack actuator housing. The module contains the engine Oil Pressure Sensor, the Boost Pressure Sensor and the protective signal conditioning circuitry.