30 SENR9977 Systems Operation Section 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) An OEM is the manufacturer of a vehicle that utilizes a Perkins engine. Parameter A parameter is a programmable value which affects the characteristics or the behavior of the engine and/or vehicle. Parameter Identifier (PID) A PID is a numerical code that contains two digits or three digits. A numerical code is assigned to each component. The numerical code identifies data via the data link to the ECM.
g00284479 Illustration 38 Example Of Pulse Width Modulation Password A password is a group of numeric characters or alphanumeric characters. A password is designed to restrict the changing of information in the ECM. The electrical engine systems require correct customer passwords in order to change customer specified parameters. The electrical engine systems require correct factory passwords in order to clear certain logged events. Factory passwords are also required in order to change certain engine specifications. Rated Fuel Position (“Rated Fuel Pos”) The rated fuel position indicates the maximum allowable fuel position (longest injection pulse).
The rated fuel position will produce rated power for this engine configuration. Reference Voltage The reference voltage is a regulated voltage that is used by the sensor in order 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. Personality Module The personality module is the module in the ECM which contains all the instructions (software) for the ECM and performance maps for a specific horsepower family. Updates and rerates are accomplished by electronically flashing in new data.
The updates and rerates are flashed in using the electronic service tool. Service Program Module (SPM) The SPM is a software program on a computer chip that was programmed at the factory. Power Take-Off (PTO) The PTO is operated with the cruise control switches or dedicated inputs from the PTO. This mode of operation permits setting constant engine rpm when the vehicle is not moving or when the vehicle is moving at slow speeds. 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 vehicle’s frame.
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 “on-time” that is divided by the percent of “off-time”. A PWM signal is generated by the Throttle Position Sensor. 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 Surge A speed surge is a sudden brief change in engine rpm. Speed-timing Sensor The speed-timing sensor is a sensor that provides a Pulse Width Modulated signal to the ECM.
The ECM interprets this signal as the crankshaft position and the engine speed. Subsystem A subsystem is a part of the engine system that relates to a particular function.