851869 1 Mercury COVER

Introduction
This Special Instruction provides information on customer interface for CG137 A4 Engines.Note: Do not perform any procedure in this publication or order any parts until you understand the information that is contained in this publication.Control System Overview
The CG137 control system consists of the A4 Electronic Control Module (ECM), connected to an array of sensors and control devices used by the ECM to monitor, control, and protect the engine. A "local" CAN data link is used on the engine to allow the ECM to communication with various intelligent control and I/O devices. The spark plugs are driven by the ECM, via ignition transformers at each cylinder.A CAN data link is used to connect the ECM to other devices including the optional Cat control panels, and the Cat® Electronic Technician (Cat ET) service tool. A global data link is also available for connection to a customer CAN network.Refer to the Operation and Maintenance Manual and individual engine Schematic for individual electrical system component locations on the engines.
Illustration 1 g06020388
Block diagram of the CG137 A4 control system
Power Supply Requirements
The CG137 control system uses customer provided 24 VDC for control power. The customer is required to provide 24 VDC +/- 2 VDC to the engine terminals under all operating conditions. Current (amperage) requirements for the engine and optional control panels are shown below.General Power Requirements
Power Supply current capability:
20A Minimum, maximum ripple voltage of 150 mVThe amperages draw of an operating engine and control panel are approximately:
CG137 Steady State Current – 6.75A – Engine Running
CG137 Peak Current – 17.25A – At Power up
Optional Operator Control Panel (OCP) – 0.9AControl Panels
The optional OCP provides for operator interface and control with a 5.5 inch monochrome display for engine monitoring.Operator Control Panel
The main component of the Operator Control Panel (OCP) is the electronic OCP Module. Some of the functions include within the OCP are:
Sending start and stop signals to the engine
Providing visual indications when warning or shutdown events occur
Displaying engine information
Displaying Suspect Parameter Number (SPN) and Failure Mode Identifier (FMI) information for events
Programming set points for the standard OCPRefer to System Operation and Troubleshooting, Testing and Adjusting, UENR3193 for a complete description of OCP functions and operation.
Illustration 2 g03849575
OCP
Illustration 3 g06011240
Enclosed OCP
The OCP panel includes all the components mounted within an enclosure and is designed to meet NEMA 4 requirements.Grounding
Illustration 4 g03849593Proper grounding is necessary for optimum engine performance and reliability. Improper grounding can result in uncontrolled or unreliable electrical circuit paths that can damage the bearing surfaces and aluminum components. These uncontrolled electrical paths can also degrade the engine electronics and communications. All grounding connections must be robust to ensure proper function. Check to see that all grounds are secure and free of corrosion.All grounding connections must be tied to a robust earth ground, which is typically a metal stake dedicated to the purpose of providing an electrical path to the earth. Each individual electrical system should be tied to the ground stake with its own cable, and all connections on these ground paths must be protected from corrosion to ensure minimal resistance along the path.The primary ground for the engine electrical system is the connection to the battery negative terminal. Attachments such as the charging alternator must be grounded to the battery negative terminal with a cable capable of carrying the full charging current of the alternator.The engine block must also be grounded, but by a separate path other than path of the engine electrical components. Do not ground the battery negative terminal to the engine block. The grounding connection on the block can be any of the unused bolt holes on the end housings. The housings are bolted to the block in multiple locations ensuring a robust conductive path between the block and housings. Choose the connection location to provide an electrically robust connection to the ground strap, and to ensure the shortest practical path to the earth ground.Connect the battery negative terminal to the earth ground with a minimum #6 AWG cable or braided strap. Ground the engine block to the earth ground with a separate ground strap. Grounding straps are to be furnished by the customer.If rubber couplings are used to connect the engine cooling system to the external piping and radiator, those external systems can become electrically isolated from the engine. Because there is no electrical path between them, a potential difference can exist. Electrically couple the two piping systems (on-engine and external) by using grounding cables across the rubber couplings to eliminate any potential difference.OCP Customer Electrical Connections
Control Wiring
Illustration 5 g06011245All electrical control connections to the engine are made at the ECM enclosure, on top of the engine at the front.Power Supply Connection