3126B MARINE ENGINE Caterpillar

Electronic System Overview

Usage:

This document provides necessary information for the correct electrical/electronic installation and application of the 3126B Marine Engine.

Engine Functions

Electronic Governing

An electronic governor with a full speed range is used. The electronic governor is isochronous at Low Idle through High Idle or the programmed top engine limit. The electronic control system has full control of the fuel delivery to the engine.

Fuel To Air Ratio Control (FARC)

The mechanical Fuel Ratio Control is eliminated. Electronic control of the fuel to air ratio provides optimum performance while limiting emissions.

Fuel Injection Timing

Fuel injection timing varies as a function of engine operating conditions to optimize the engine performance. Engine performance is determined by the following conditions:

* cylinder pressure

* emissions

* exhaust temperature

* fuel consumption

Shaping of Torque Rise

Electronic controls provide increased flexibility to customize the torque curve over a wide range of engine speeds.

Programmable Monitoring System

The Programmable Monitoring System determines the level of action that is taken by the ECM in response to a condition that can damage the engine. These conditions are identified by the ECM from the signals that are produced from the following sensors:

* Inlet Air Temperature Sensor

* Coolant Temperature Sensor

* Oil Pressure Sensor

* Transmission Oil Temperature Sensor (if installed)

* Transmission Oil Pressure Sensor (if installed)

The Transmission Oil Pressure Sensor and Transmission Oil Temperature Sensor can be programmed to Disable (YES). If a sensor is disabled, then all event diagnostics associated with the sensor will be ignored.

Table 1: Parameter Table

* See Oil Pressure Map

** Engine Overspeed Shutdown disables injection when the engine speed exceeds 3220 rpm. The injection is enabled when the engine speed drops below 2800 rpm.

Figure 1 - Low Oil Pressure Map

Table 2: Event Codes

Tools Required

Installation Tools

Basic electrical installation tools required are listed below. Additional sensors, lamps, connectors, etc, may be required.

Table 3: Basic Electrical Installation Tools

Service Tools

The Caterpillar Electronic Technician (ET) Service Tool is designed to help the service technician analyze and locate faults or problems. An ET Service Tool is required to perform certain sensor calibrations electronically and to read or program engine parameters.

Caterpillar Electronic Technician (ET) requires a personal computer with the ET software installed and a Caterpillar Communication Adapter to translate from the data link to the computer RS-232 port.

The ET communicates with the ECM to perform the following functions:

* read/display diagnostic codes and event codes

* read sensor signals such as engine speed, oil pressure, or coolant temperature

* control the electronic calibration of the Throttle Position Sensors and Speed Timing Sensors through the ECM.

Electronic Technician (ET) Electronic Service Tool

ET requires an IBM compatible computer (laptop) and software. The software allows the user to program ECM parameters, read and display sensor values and switch status, perform diagnostic tests and calibrate sensors. Table 4, "Required Tools for Electronic Technician (ET)," outlines the tools required to use ET.

Table 4: Required Tools for Electronic Technician (ET)

Service Manual

Connecting ET And The Communication Adapter Tool

The Communication Adapter Tool operates on the battery voltage supplied by the engine electrical system. Use the following procedure to connect ET and the Communication Adapter Tool to the engine.

1. Turn the keyswitch to the OFF position.

2. Connect the Service Tool Harness Cable between the J60 Service Tool Connector and the Communication Adapter Control connector.

3. Connect the Communication Adapter Service Tool to the PC using the appropriate cable as shown.

Turn the keyswitch to the ON position to begin testing. Do not start the engine unless instructed to start the engine by the "3126B Marine Engine Troubleshooting" manual. The ET and Communication Adapter Tool will operate with the engine running or with the engine off provided the keyswitch is in the ON position.

Figure 2 - Communication Adapter II Connections

3126B HEUI Component Diagram

Figure 3 - Component Diagram

Sensor and Wiring Harness Connector Locations

Figure 4 - Sensor Locations and Wiring Harness Connectors on the Engine

Switch Requirements and Considerations

Switch Specifications

All OEM provided switches connected to the electronic control system must be a two wire design and externally connected to the Negative Battery Bus Bar. Internally grounded or case grounded switches must not be used.

Voltages supplied to switches by the electronic control system will normally not exceed 24 VDC. Normal current through the switches will not exceed 5.0 milliamperes.

Contact chatter and momentary opening or closing of the switches should not exceed 100 milliseconds in duration. The switches should not open or close due to vibration or shock normally found in the application.

Contact plating should not corrode or oxidize. Gold plated switch contacts are recommended.

When a switch contact is opened or the wiring harness has an open circuit, the internal pull up voltages of the ECM force the respective input to the positive battery. The closure of a switch that is installed by the OEM must short circuit the switch input to the Negative Battery Bus Bar connection of the ECM connector P1.

All switches are supplied by the OEM. If a problem occurs that has an undetermined cause, install an Electronic Service Tool. Observe the display status screen of the Electronic Service Tool to determine the status of the switch.

Voltage Thresholds Measured At The ECM

Voltage in Low

When any switch contacts are closed, the following voltage changes must be less than 0.9 VDC between the respective control input and the Negative Battery Bus Bar:

* ground potential differences

* switch voltage drops

* wiring harness voltage drops

Voltage in High

When any switch contacts are open, the effective resistance between the pin-to-pin leakage paths in any of the following components must not result in an effective resistance of less than 5K Ohms between the respective control input and the ECM negative battery input:

* connectors

* harnesses

* switches

OEM installed switches must be connected to the Negative Battery Bus Bar.

Customer Installed Switches

Switch Connections

Table 5: Customer Connector Pin Connections for Switches

Figure 5 - 3E-8766 and 3E-8768 Switches

(R) ON (top or left)

(S) NONE (center)

(T) OFF (bottom or right)

(1) Actuator orientation tabs

Figure 6 - Schematic of 3E-8766 and 3E-8768 Switches

When the switch contacts 2 and 3 are closed, the backlight connected to switch terminals A and B turns on.

Figure 7 - 3E-8772 Switch

(R) ON (top or left)

(S) OFF (center)

(T) ON (bottom or right)

(1) Actuator orientation tabs

Figure 8 - Schematic of 3E-8772 Switch.

When the contacts 1 and 2 of the switch are closed, the backlight connected to switch terminals A and B turns on.

When the contacts 5 and 6 of the switch are closed, the backlight connected to switch terminals C and D turns on.

Wire Size Requirements

The size of the wire that is used to connect all electrical components must be adequate size for the maximum current in the circuit. All positive battery connections and all negative battery connections to the J61 Customer Connector should use 14 AWG wire.

The circuit from the Negative Battery Bus Bar to the bridge displays should be made with a minimum of 12 AWG wire. The circuit from the Negative Battery Bus Bar to the bridge displays must be a dedicated circuit that has no other connected components.

Using 143-5018 Data Cable for the Cat Data Link circuit is RECOMMENDED. This cable consists of a twisted pair of 18 AWG wire. All other electronic system circuits should use 16 AWG wire.

OEM Wiring Harness

Figure 9 - Correct Wiring Harness Routing at the Connector

(A) 25 mm (1.0 inch) perpendicular length of wire

(1) No gap between wire and seal

The routing of the OEM wiring harness should be designed so that the curvature of the wire from the connector meets the standards that are shown in Figure 9 - "Correct Wiring Harness Routing at the Connector".

Special attention should be given to the routing of wiring that is near the following components:

* valve cover

* wiring harness connector

* components mounted on the engine

* customer connector

* display connectors

Figure 10 - Incorrect Wiring Harness Routing at the Connector

(2) Gap between the wire and the seal

Figure 10 - "Incorrect Wiring Harness Routing at the Connector" shows the incorrect routing of the wiring harness. When the curvature of the wire is too close to the connector, the seal is stretched away from the wire within the connector. This stretching of the seal provides an opening for the entry of moisture.

Each pin or socket should have only one wire crimped into it. The wire should exit from the connector perpendicular to the connector. The perpendicular length of the wire should be 25 mm (1.0 inch) before any curvature exists in the wire.

The radius of a bend in the bundle of wires of the wiring harness should be greater than twice the diameter of the bundle of wires.

Twisted pair wiring should be used for the CAT Data Link. Twisted pair wiring should have a minimum of one twist per 25 mm (1.0 inch). The twisted pair wires should not be twisted closer than 25 mm (1.0 inch) from the connector to avoid stress on the seal.

The acceptable diameter of the insulation for a wire that is connected to the 40 pin Customer Connector is 2.54 to 3.43 mm (0.100 to 0.135 inch). The acceptable diameter of the insulation for a wire that is connected to an HD-10 connector is 2.54 to 3.81 mm (0.100 to 0.150 inch). The acceptable diameter of the insulation for a wire that is connected to a DT connector is 2.40 to 3.68 mm (0.095 to 0.145 inch).

Caterpillar recommends that all ring terminals and splices to be sealed using Raychem ES2000 adhesive lined heat shrink sleeve or equivalent.

Installation of Pins, Sockets, and Connector Sealing Plugs

Figure 11 - Insertion of Plug in Unused Slot

Figure 12 - Insertion of Plug in Unused Slot

The following procedures should be performed to ensure the correct installation of pins and sockets in connectors:

* Do not solder the sockets and pins to the wires.

* Never crimp more than one wire in a socket or pin.

Figure 13 - Correct Pin and Socket Connections

* All sockets and pins should be crimped on the wires. Use the 1U-5804 Crimping Tool for 12-18 gauge wire.

* All unused slots for sockets and pins must be filled with sealing plugs to ensure that the connector is sealed.

* The sealing plugs are installed from the wire entry end of the plug or receptacle.

* The sealing plugs that are installed in unused slots must seal correctly. Refer to Figure 12 - "Insertion of Plug in Unused Slot" for correct installation of plugs. The plug rests against the seal. The plug does not insert into the seal.

Caterpillar Wiring Harness

Do not modify the Caterpillar wiring harness.

The J61 40-Pin Customer Connector is used to interface the engine electronics with the wiring harness provided by the customer.

The electronic control system is designed to operate with a 12 or 24 VDC electrical system. The control system is protected against jump start conditions and short circuits to the battery.

The 70 pin ECM connectors and the 40 pin Customer Connector must have sealing plugs inserted in all of the unused sockets to ensure proper sealing.

ECM and Customer Connectors

Ensure that the Allen head bolt in the ECM Connectors J1 and J2 and the Customer Connector P61 are tightened to a maximum torque of 6.0 Nm (53 lb in). ECM Connectors J1 and J2 are located on the ECM. The Allen bolts for J1 and J2 are on the connector and are shown on Figure 14 - "Wiring Harness and Connectors for ECM and Customer Connector".

The Customer Connector P61 is shipped with the engine. Perform the pull test on each wire and the respective pin or socket from the wire entry end of each connector. The force for the pull test is 45 N (10 lb).

When the pull test is performed, the wire and the socket or pin should remain in the connector. The pull test ensures that the wire was correctly crimped in the socket or pin. Also, the pull test ensures the socket or pin was correctly inserted through the wire entry end of the connector.

Figure 14 - Wiring Harness and Connectors for ECM and Customer Connector

HD-10 Connector

Figure 15 - HD-10 Plugs and Receptacles

Ensure that the wires in the plug align with the matching wires in the receptacle. Ensure that the index markings on the plug and the receptacle are aligned.

Rotate the plug until the plug slips into the receptacle. Rotate the coupling approximately 90 degrees until a click sound is heard. Ensure that the plug and the receptacle cannot be pulled apart.

The acceptable range for the diameter of the insulation of the wire that is used with the connectors is 2.54 to 3.81 mm (0.100 to 0.150 inch).

DT Connector and Packard Connectors

Figure 16 - Deutsch DT Connector and Packard Connectors

A DT connector has a wedge that locks the pins and sockets in place. The wedge can be removed and replaced without cutting the wires. When the two halves properly lock together, a click sound should be heard when the receptacle is inserted in the plug. The two mating halves can not be pulled apart.

The acceptable range for the diameter of the insulation on the wire that is used with the DT connectors is 2.24 to 3.68 mm (0.088 to 0.145 in).

Inspect the plug and the receptacle to ensure that the following components are correctly installed:

* The connector seals are seated.

* The pins and sockets are not damaged.

* The pins and the sockets are securely installed on the wires. Perform the Pull Test.

* The correct number of pins and sockets exist on both halves of the connector.

* The pins align correctly with the sockets.

* The locking tabs are not damaged. Replace the connector if the tab is damaged.

* The wedges are not damaged. The 147-6456 DT wedge removal tool aids in the removal of the wedges.

Programmable Parameters

Many programmable parameters affect engine operation. Certain parameters that affect Marine Engine operation may be changed with an Electronic Service Tool.

Parameters are stored in the ECM, and may be protected from unauthorized changes by passwords. These parameters are System Configuration Parameters and Customer Specified Parameters. Any parameter can be read, however, passwords may protect parameters from unauthorized changes. System Configuration Parameters can be altered only with the proper factory passwords. Customer Passwords, if programmed, are required to change Customer Parameters.

System Configuration Parameters

System Configuration Parameters affect emissions or power of the engine. They are programmed at the factory and would normally never need to be changed through the life of the engine. System Configuration Parameters must be reprogrammed if an ECM is replaced, but not if the Personality Module is replaced (unless the engine rating changes). Proper values for these parameters are stamped on the Engine Information Plate (or film) located on the valve cover or inlet manifold.

Refer to System Configuration Parameters and Customer Specified Parameters for more details on how to receive and use factory passwords and customer passwords.

Customer Specified Parameters

Customer Specified Parameters allow the engine owner to influence how an engine operates. Customer parameters may be changed repeatedly as a customer changes the operation or as new operators are assigned. Customer passwords, if programmed, are required to change these parameters.

Table 6: Programmable Parameters

ECM Configuration Parameters

System configuration parameters affect the emissions or the power of the engine. These parameters are programmed at the factory. The system configuration parameters would normally never need to be changed through the life of the engine. However, the parameters must be reprogrammed if an ECM is replaced. The factory passwords are required to change the system configuration parameters.

The correct values of the system configuration parameters are stamped on the engine information plate. This plate is located on the valve cover or the deaerator.

Full Load Setting (FLS)

The number for the full load setting represents the adjustment for the fuel system that is performed in the factory.

A new ECM must have the full load setting programmed to avoid generating the 268-02 Check Programmable Parameters diagnostic code. The flash code is 56.

Full Torque Setting (FTS)

The full torque setting is similar to the full load setting. If the full torque setting is not programmed, the 268-02 Check Programmable Parameters diagnostic code will be generated. The flash code is 56.

Personality Module Code

The personality module code prevents the incorrect use of the personality module for the engine. A different code exists for each family of engines.

If a personality module is replaced, the code that is stored in the ECM must match the code of the new personality module. If the codes do not match, the engine will not start. Also, the 253-02 Personality Module Mismatch diagnostic code will be generated. The flash code is 59.

When the engine is "rerated", the Electronic Service tool will prompt the user for factory passwords. If factory passwords are not entered the engine will not start.

Engine Serial Number

The engine serial number should be programmed to match the engine serial number that is stamped on the engine information plate.

The engine serial number is programmed to "0XX00000" on a new ECM.

Customer Specified Parameters

Customer specified parameters allow the owner of the engine to determine some characteristics for the operation of the engine. Some parameters may affect the operation of the engine. When the customer changes the operation of the vessel or engine or assigns new operators, the customer parameters may need to be changed. Customer passwords may be required to change the parameters.

Selection Number for Engine Power Rating

The selection number for the engine power rating is the rating number for the family of engines. The personality module defines the family of engines. A family of engines may contain more than one rating. The rating number defines the rating that is used.

Equipment ID

The Equipment ID is the identification number or name of the vessel. The Equipment ID is assigned by the customer for reference by the customer. The Equipment ID is not a required parameter.

Engine Location

If three or less engines are installed, the engine location must be programmed into the ECM as:

* Port

* Center

* Starboard

The default setting is "Engine 1".

If more than three engines are installed, program the ECM locations to:

* Engine 1 - equivalent to the Center location

* Engine 2 - equivalent to the Port location

* Engine 3 - equivalent to the Starboard location

* Engine 4

* Engine 5

NOTE: After you change the engine location, you must turn the keyswitch off and then on for the engine location to be valid.

NOTE: Secondary Throttle Enable Status, Engine Location, and Number of Synchronized Engines Configuration must be programmed in this order:

* Number of Synchronized Engines Configuration

* Engine Location

* Secondary Throttle Enable Status

The Number of Synchronized Engines Configuration parameter determines what location names can be used and whether the Secondary Throttle Enable Status parameter is automatically set to ON.

Number of Synchronized Engines

The number of engines synchronized to a throttle must be programmed into the ECMs.

NOTE: Secondary Throttle Enable Status, Engine Location, and Number of Synchronized Engines Configuration must be programmed in this order:

* Number of Synchronized Engines Configuration

* Engine Location

* Secondary Throttle Enable Status

The Number of Synchronized Engines Configuration parameter determines what location names can be used and whether the Secondary Throttle Enable Status parameter is automatically set to ON.

Secondary Throttle Enable Status

When the Secondary Throttle Enable Status is programmed to ON, the ECM will enable the Secondary Throttle diagnostics and throttle synchronization is enabled.

* 1249-08 Secondary Throttle Position Signal Abnormal (32)

* 1249-12 Secondary Throttle Position Sensor Calibration Required (28)

If Secondary Throttle Enable Status is programmed to OFF, the ECM will disable all diagnostics and throttle synchronization will be disabled.

NOTE: Secondary Throttle Enable Status, Engine Location, and Number of Synchronized Engines Configuration must be programmed in this order:

* Number of Synchronized Engines Configuration

* Engine Location

* Secondary Throttle Enable Status

The Number of Synchronized Engines Configuration parameter determines what location names can be used and whether the Secondary Throttle Enable Status parameter is automatically set to ON.