GASKET 4563862 - Caterpillar

Introduction
Two Electronic Control Modules (ECM) are used to control the engine. One module is the master ECM and the other module is the slave ECM. Each module is an environmentally sealed unit that is mounted in a terminal box on the engine.The master ECM controls most of the functions of the engine. The master ECM monitors various inputs from sensors in order to activate relays, solenoids, etc at the appropriate levels. The master ECM supports the following five primary functions:
Engine speed governing
Air/fuel ratio control
Start/stop sequencing
Engine monitoring and protection
Control of the ignition for the left cylinder bank
Monitoring the level of detonation in the left cylinder bank
When detonation occurs in the left cylinder bank, the master ECM will adjust the timing in order to control the detonation.When detonation occurs in the right cylinder bank, the slave ECM will adjust the timing in order to control the detonation.Engine Speed Governing
The master ECM maintains the desired engine speed by controlling the actuator for the throttle. The actuator is located at the outlet from the aftercooler. The actuator is electronically controlled and electrically actuated.The master ECM issues a throttle command to the actuator via the CAN data link. The throttle command is a percentage. The value of the command can be viewed on the Caterpillar Electronic Technician (ET). The actual position of the throttle can be viewed via a pointer that is built into the throttle's mechanism.Desired engine speed is determined by the desired speed input (analog voltage or 4 to 20 mA) and parameters such as maximum engine high idle speed that are programmed into the software. Actual engine speed is detected via a signal from the speed/timing sensor. Parameters for the governor gains can be programmed with Cat ET.Air/Fuel Ratio Control
The master ECM provides control of the air/fuel mixture for performance and for efficiency at low emission levels. The system consists of an electronic fuel metering valve, output drivers in the master ECM, and maps in the master ECM. The control compensates for changes in the BTU of the fuel in order to maintain desired emission levels.The ECM maintains the engine's exhaust emissions at the levels that are required at the site. The ECM uses oxygen feedback in order to control emissions.The following steps describe the basic operation:
The ECM monitors the amount of oxygen in the exhaust via an oxygen sensor.
The ECM determines the desired flow rates for the air and for the fuel. The flow rates are determined by these factors:
Desired engine speed
Actual engine speed
Calculated engine load
The command for the flow of the fuel is sent to the electronic fuel metering valve via the CAN data link.This process is repeated continuously during engine operation.Start/Stop Sequencing
The master ECM contains the logic and the outputs for control of starting and of shutdown. The customer programmable logic responds to signals from the following components: engine control, emergency stop switch, remote start switch, data link and other inputs.When the programmable logic determines that it is necessary to crank the engine, the master ECM supplies