SENR9977 29 Systems Operation Section i02285310 Glossary of Electronic Control Terms Diagnostic Lamp A diagnostic lamp is sometimes called the check engine light. The diagnostic lamp is used to warn the operator of the presence of an active diagnostic code. Direct Current (DC) Direct current is the type of current that flows consistently in only one direction. Aftermarket Device An aftermarket device is a device or an accessory that is installed by the customer after the engine is delivered. Duty Cycle See Pulse Width Modulation.
Electronic Service Tool The Electronic Service Tool is used for diagnosing a variety of electronic controls and the Electronic Service Tool is also used for programming a variety of electronic controls. Air-To-Air Aftercooler An air-to-air aftercooler is a device that is used on turbocharged engines in order to cool inlet air that has undergone compression. The inlet air is cooled after the inlet air passes through the turbocharger. The inlet air is passed through an aftercooler (heat exchanger) that uses ambient air for cooling. The inlet air that has been cooled advances to the inlet manifold. Engine Control Module (ECM) The ECM is the engine’s control computer.
The ECM provides power to the electronics. The ECM monitors data that is input from the engine’s sensors. The ECM acts as a governor in order to control engine rpm. Before Top Center (BTC) BTC is the 180 degrees of crankshaft rotation before the piston reaches the top center position in the normal direction of rotation. Estimated Dynamic Timing Estimated dynamic timing is the estimate of the actual injection timing that is calculated by the ECM. Bypass Circuit A bypass circuit is a circuit that is used as a substitute circuit for an existing circuit. A bypass circuit is typically used as a test circuit.
Enable Signal for the Exhaust Brake The exhaust brake enable signal interfaces the ECM to the engine retarder. This prevents the operation of the exhaust brake under unsafe engine operating conditions. Coolant Temperature Sensor The coolant temperature sensor measures the engine coolant temperature. The sensor sends a signal to the ECM. The engine’s coolant temperature is used in Cold Mode operation. Coolant temperature is also used in order to optimize engine performance. Failure Mode Identifier (FMI) The FMI describes the type of failure that was experienced by the component. The codes for the FMI were adopted from the standard practices of SAE (J1587 diagnostics).
Code See the Diagnostic Code. Customer Specified Parameters A customer specified parameter is a parameter that can be changed. A customer specified parameter’s value is set by the customer. These parameters are protected by customer passwords. Flash Memory See the Personality Module. Fuel Ratio Control (FRC) The FRC is a limit that is based on the control of the fuel to the 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.
Data Link The data link is an electrical connection that is used to communicate with other electronic devices that have microprocessors. 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. Fuel Position The fuel position is a signal within the ECM. The signal is from the electronic governor. The signal goes to the fuel injection control. The signal is based on the desired engine speed, the FRC, the rated position, and the actual engine speed. Desired RPM The desired rpm is input to the electronic governor within the ECM.
The electronic governor uses the signal from the Accelerator Pedal Position Sensor, the Engine Speed Sensor, the Cruise Control, and the Customer Parameters in order to determine desired rpm. Harness The harness is the bundle of wiring that connects all the components of the electrical engine system. Hertz (Hz) Hz is the measure of frequency in cycles per second. Diagnostic Code A diagnostic code is sometimes called a fault code. A diagnostic code is an indication of a problem or event in the electrical engine systems. Intake manifold temperature sensor The intake manifold temperature sensor is a sensor that measures the intake air temperature. The sensor also sends a signal to the ECM.