804173 Mercury PILOT JET (#42)

Electronic Controls
The electronic controller consists of two main components: the Electronic Control Module (ECM) and the Personality Module. The ECM is the computer which controls the engine. The Personality Module is the software which controls how the computer behaves. The two must be used together: neither can do anything by itself.Rack Controls
The rack mechanism on a 3408/3412 engine is moved by a servo valve which receives oil pressure from the fuel injection pump. However, the servo spool is moved by a solenoid (BTM) rather than by a linkage controlled by flyweights and springs.The ECM determines a "desired engine speed (rpm)" based on the throttle position, and customer specified parameters. The ECM tries to maintain the desired engine speed (rpm) by sensing actual engine speed using the main engine speed sensor or the backup speed sensor, then controlling the rack to achieve the desired engine speed. To move the rack, ECM adjusts the voltage to the rack solenoid (BTM) to increase or decrease rack. More voltage results in more rack. The ECM knows how far the rack moved by reading the rack position sensor. The ECM increases or decreases the voltage to the rack solenoid until it senses the rack is at the desired position. The ECM sets certain limits on rack motion. "FRC Rack" (Fuel Ratio Control Rack) is a rack limit used to reduce the amount of acceleration smoke. It works similar to a mechanical engine FARC (Fuel Air Ratio Control); when the ECM senses a higher inlet manifold (boost) pressure (more air into cylinders), it increases the FRC Rack limit, which allows more fuel into the cylinders. "Rated Rack" is a rack limit based on rated power of the engine. It is similar to the rack stops and torque springs on a mechanical engine. It provides a power output limit and torque curves for a specific engine family and rating. All of these limits are programmed by the factory into the personality module.Programmable Parameters
Certain parameters that affect the 3408/3412 Diesel Engine operation may be changed with an electronic service tool (ECAP). These parameters are stored in the ECM.These parameters are either "System Configuration Parameters" or "Customer Parameters". System Configuration Parameters are those that effect power ratings family or emissions. Customer Parameters are those that affect Low Idle Engine Speed Setting and engine location (PORT, STBD).Passwords
"System Configuration Parameters" are not protected by factory passwords."Customer Parameters" are protected by customer passwords. The customer passwords are programmed by the customer.Self-Diagnostics
The ECM electronics have some ability to diagnose itself. When a problem is detected, a diagnostic code is generated and the diagnostic lamp flashes the diagnostic code. In most cases, the code is also stored in permanent memory in the ECM.Codes that represent current faults are called ACTIVE. They indicate that a problem of some kind currently exists. They should always be serviced first. See the section on "Troubleshooting Diagnostic Codes" in this manual for more details.Codes stored in memory are called LOGGED. Since the problem may have been temporary or may have been repaired since the time it was logged, logged codes don't necessarily mean something needs to be repaired. Instead they are meant to be an indicator of probable causes for intermittent problems. In addition, some logged codes record "events", rather than failures. Codes not requiring passwords to clear are automatically deleted after 100 ECM hours. See the section on "Troubleshooting Diagnostic Codes" in this manual for more details.Overspeed Protection System
The Overspeed Protection System is designed with controls built into a single unit to monitor several functions at the same time. The functions that the system monitors are:Engine Overspeed (OS)
This is an adjustable engine speed setting (normally 127% of rated speed) that prevents the engine from running at a speed that could cause damage.An overspeed condition will cause relay SR1 to open and deenergize the shutoff solenoid. The deenergizing of the shutoff solenoid will stop the fuel to the engine causing the engine to shutdown. If overspeed switch is failed, then a jumper can be added to bypass the relay SR1 and restart the engine.Crank Termination (CT)
This is an adjustable engine speed setting that signals the starter motor that the engine is firing and cranking must be terminated. When the speed setting is reached, a switch will open to start the engine hour meter.Trolling Mode
The trolling switch is used to activate trolling mode operation. During trolling mode operation the full range travel of the throttle lever will cause the engine speed to change from low idle engine speed to maximum programmable trolling speed. The trolling mode will only be activated by the electronic control module when engine speed is within 30 rpm of low idle speed. The trolling mode can also be activated when the engine is not running.Engine Synchronization (Power Link)
Engine Synchronization links the electronic controls of both engines to a single throttle lever. A switch is installed (OEM supplied) linking the two throttle controls. The operator uses the switch to transfer the control of both engines to either PORT or STBD throttle. Engine synchronization is accomplished by synchronizing either PORT throttle or STBD throttle. This will enable the operator to have full throttle control of both engines, even if one throttle is not functioning.The synchronization switch can also be used to transfer throttle control to the second throttle and maintain full control of both engines, if one throttle fails.Computerized Monitoring System (CMS)
Computerized Monitoring System (CMS) is an electronic monitoring system used to display engine/transmission information. The System Diagnostic indicators, on the right side of the display, identify conditions that are present. If an indicator comes on, refer to the procedures indicated below to troubleshoot the condition. For more information on the CMS, refer to 3408/3412 High Performance Marine Engine Operation and Maintenance Manual, Form No. SEBU6497.System Warning Outputs
The electronic control system provides six different warning lamps to warn the operator about engine and transmission condition. These lamps can be used to obtain status of Engine Low Oil Pressure, High Coolant Temperature, Low Coolant Level, Low Boost