CORE AS 1253944 - Caterpillar

Introduction
Electronic Control Modules (ECM) are used to control the engine. Each module is an environmentally sealed unit that is mounted in a terminal box on the engine. The following modules are standard:Master ECM - 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 primary functions:
Engine speed governing
Air/fuel ratio control
Start/stop sequencing
Engine monitoring and protection
Control of the ignition and detonation of the left cylinder bankSlave ECM - The slave ECM supports the control of ignition and of detonation of the right cylinder bank.The master ECM and the slave ECM communicate via the Cat Data Link.Start/Stop Sequencing
The master ECM contains the logic and the outputs for control of engine starting and of engine shutdown. Program this logic through the configuration screens that are in Caterpillar Electronic Technician (ET). The logic responds to signals from the following components:
Engine control switch
Emergency stop switch
Remote start switch
Data link
Prelubrication system
Other inputsWhen the programmable logic determines that it is necessary to crank the engine, the ECM supplies +Battery voltage to the relay for the starting motor. The ECM removes the voltage when the programmable crank terminate speed is reached or when a programmable cycle crank time has expired.The engine must be equipped with an energize-to-run Gas Shutoff Valve (GSOV). The source of the voltage to the GSOV depends on the engine's configuration. The GSOV may be energized by the customer's equipment or by the engine's control system.If the engine's control system controls the GSOV, the ECM supplies +Battery voltage to the GSOV whenever the programmable logic determines that fuel is required to operate the engine.For more information on programmable parameters, see Troubleshooting, "Programming Parameters".Ignition Control
The ECM provides variable ignition timing that is sensitive to detonation.Each cylinder has an ignition transformer that is located under the valve cover for the cylinder. To initiate combustion, the ECM sends a pulse of approximately 100 volts to the primary coil of each ignition transformer at the appropriate time and for the appropriate duration. The transformers step up the voltage in order to create a spark across the spark plug electrode.Detonation sensors monitor the engine for excessive detonation. The engine has detonation sensors that monitor each cylinder. The sensors generate data on vibration that is processed by the ECM in order to determine detonation levels. If detonation reaches an unacceptable level, the ECM retards the ignition timing of the cylinder that is experiencing the detonation. If retarding the timing does not limit detonation to an acceptable level, the ECM shuts down the engine. The maximum timing retard that is allowed due to detonation is six degrees from the desired timing.The ECM provides extensive diagnostics for the ignition system. The ECM also has an input that is used to toggle between different settings for the ignition timing. This allows the engine to be easily converted for use with alternate fuels.Engine Speed Governing
The ECM maintains the desired