3176B MARINE ENGINE Caterpillar

1.0 3176B Electronic System Overview

Usage:

System Operation

The 3176B Marine Engines were designed for electronic control. The injection pump, fuel lines and nozzles used in traditional Caterpillar engines have been replaced with an electronic unit injector in each cylinder. A solenoid on each injector controls the amount of fuel delivered by the injector. An Electronic Control Module (ECM) sends a signal to each injector solenoid, to provide complete control of the engine.

Electronic Controls

The 3176B Marine Engines electronic system consists of two main components: the Electronics [Electronic Control Module (ECM) and Sensors] and the Personality Module. The ECM is the computer which controls the 3176B engine. The Personality Module contains the software which controls how the ECM behaves (the personality module stores the operating maps that define horsepower, torque curves, rpm, etc). The two must be used together: neither can do anything by itself.

The ECM determines a "desired rpm" based on the throttle signal and certain diagnostic codes. The ECM then maintains the desired engine rpm by sensing actual engine rpm and deciding how much fuel to inject in order to achieve the desired rpm.

Fuel Injection

The ECM controls the amount of fuel injected by varying signals to the injectors. The injectors will inject fuel ONLY if the injector solenoid is energized. The ECM sends a 100 volt signal to the solenoid to energize it. By controlling the timing and duration of the 100 volt signal, the ECM can control injection timing and the amount of fuel injected.

The ECM sets certain limits on the amount of fuel that can be injected. "FRC Fuel Pos" is a limit based on boost pressure to control the fuel to air ratio, for emissions control purposes. When the ECM senses a higher boost pressure (more air into cylinder), it increases the "FRC Fuel Pos" limit (allows more fuel into cylinder). "Rated Fuel Pos" is a limit based on the horsepower rating of the engine. It is similar to the rack stops and torque spring on a mechanically governed engine. It provides horsepower and torque curves for specific engine family and rating. All of these limits are programmed at the factory into the Personality Module and are not programmable in the field.

Injection timing depends on engine rpm, load and other operating factors. The ECM knows where top center on cylinder number one is from the signal provided by the engine Speed/Timing Sensor. It decides when injection should occur relative to top center and provides the signal to the injector at the desired time.

Caterpillar Engine Monitoring

Caterpillar provides a factory installed Engine Monitoring system. The Caterpillar Engine Monitoring system monitors engine oil pressure, coolant temperature, intake manifold air temperature, and coolant level. The oil pressure, intake manifold air temperature, and coolant temperature sensors are standard on all engines. The Vessel OEM is responsible for providing the coolant level sensor and the associated harness. The coolant level sensor is the only individually selectable component of Caterpillar Engine Monitoring. It is ENABLED or DISABLED through a Customer Programmable Parameter.

Caterpillar Engine Monitoring can be programmed to four different modes; OFF, WARNING, DERATE and SHUTDOWN with the additional option of enabling or disabling the Coolant Level Sensor. The Coolant Temperature, Oil Pressure, and Coolant Level (if enabled) Sensors will operate in the Engine Monitoring Mode selected. For example, if DERATE mode were selected, the engine will derate engine HP if the Coolant Temperature, Oil Pressure, or Coolant Level (if enabled) Sensors detect conditions exceeding acceptable limits. The Oil Pressure Sensor can not be selected for WARNING, while the Coolant Temperature Sensor operates in a different mode such as DERATE.

An excessive Intake Manifold Air Temperature will not derate the engine. If the Engine Monitoring Mode is programmed to DERATE, and a 105-11 Very High Intake Manifold Air Temperature Diagnostic Code is Active, the engine will Warn, but will not Derate the engine.

Caterpillar Engine Monitoring Off

If Caterpillar Engine Monitoring is programmed to OFF, the control system disables those diagnostics associated with Caterpillar Engine Monitoring as shown in the following table.

Diagnostic Codes Enabled for Caterpillar Engine Monitoring

The engine will still use the Coolant Temperature Sensor signal for Cold Mode operation, and the diagnostics available for flagging incorrect sensor operation (Coolant Temp Sensor Open/Short Circuit). The Intake Manifold Air Temperature Sensor signal will also still be used for timing advance. The 105-00 High Intake Manifold Air Temperature Warning and 105-11 Very High Intake Manifold Air Temperature will be logged regardless of the engine monitoring mode. The Oil Pressure Sensor signal will be ignored. Because the Oil Pressure Sensor and Coolant Level Sensor harnesses are still present on the engine, the harness could cause a problem in the event it had a short circuit in the supply wire to ground. Therefore, these items should not be excluded from diagnostic procedures.

Caterpillar Engine Monitoring Warning Mode Operation

If the system is programmed to WARNING the ECM will indicate the diagnostic codes, listed in the following tables, are active through the Check Engine/Diagnostic Lamp, and will also turn the Warning Lamp on solid when the necessary conditions exist. No further action occurs if the ECM is programmed to WARNING.

Caterpillar Engine Monitoring Derate Mode Operation

If the system is programmed to DERATE the ECM will indicate the diagnostic codes listed in the following table are active through the Check Engine/Diagnostic Lamp. Conditions causing Diagnostic Codes 100-01 Low Oil Pressure Warning, 111-01 Low Coolant Level Warning, 105-00 High Intake Manifold Air Temperature Warning and 105-11 Very High Intake Manifold Air Temperature Warning will cause the Warning Lamp to come on solid. Conditions causing Diagnostic Codes 110-00 High Coolant Temperature Warning, 110-11 Very High Coolant Temperature Warning, 100-11 Very Low Oil Pressure Warning and 111-11 Very Low Coolant Level Warning will cause the Warning Lamp to begin to flash. The Warning Lamp flashes whenever the engine is derated. During DERATE mode the Warning Lamp will begin to Pulse (the Diagnostic/Check Engine Lamp will flash indicating the presence of an Active diagnostic code), and the available engine power will be limited (if due to Very Low Oil Pressure, engine speed is also limited).

There are tables and graphs shown on the following pages detailing Caterpillar Engine Monitoring Operation with respect to each Diagnostic Code and sensor of the system.

Programmed to WARNING

Programmed to DERATE

Programmed to SHUTDOWN

Caterpillar Coolant Temperature Engine Monitoring Operation

The following graph indicates operation of Caterpillar Coolant Temperature Engine Monitoring.

This graph indicates a Coolant Temperature of 103°C (217°F) triggers ECM action. The three tables on the previous page indicate the affect of the different programmable levels (WARNING, DERATE, & SHUTDOWN).

If the ECM has been programmed to DERATE, the ECM will begin to derate available power according to 1°C (1.8°F) temperature changes as indicated by the four "steps". Note the "steps" are limited to reducing available power at a rate of 10 percent per second maximum. Each plateau of the steps indicates the available power has been reduced by 25 percent as follows:

HP Reduction = 25% X (rated HP - 160 HP)

If the Coolant Temperature continues to increase until it reaches 106°C (223°F), a 110-11 Very High Coolant Temperature Diagnostic Code will be Active. At this point the engine power is limited to 160 HP. If the Coolant Temperature continues at or above 106°C (223°F), the engine will shutdown in 20 seconds after reaching this temperature threshold (if programmed to SHUTDOWN). The minimum time to Shutdown is 30 seconds if the engine has been running for at least 30 seconds.

The engine can be restarted an unlimited number of times following a Caterpillar Engine Monitoring Shutdown. The minimum time to shutdown is indicated below at start up and for restart following an Engine Monitoring Shutdown.

Fuel Temperature Monitoring

The Fuel Temperature Sensor monitors the fuel temperature and adjusts the ECM calculated fuel rate to compensate for fuel temperature changes. The sensor is also used to warn the operator of an excessive fuel temperature [90°C (194°F) or higher for ten minutes] using the 174-00 High Fuel Temperature Diagnostic Code. This is done because excessive fuel temperatures can adversely affect engine performance.

For fuel temperatures above 30°C (86°F) the ECM will adjust the rated fuel position to provide constant power.

Programmable Parameters

Certain parameters that affect 3176B Marine Engine operation may be changed with electronic service tools (ECAP). The parameters are stored in the ECM, and are protected from unauthorized changes by passwords.

These parameters are either "System Configuration Parameters" or "Customer Parameters". System Configuration Parameters are set at the factory and affect emissions or horsepower ratings within a family of engines. Factory passwords must be obtained and used to change System Configuration Parameters. Customer Parameters are variable and can be used to affect rpm/horsepower ratings within the limits set by the factory, Caterpillar Engine Monitoring, and PTO operation. Customer Passwords are necessary to change Customer Specified Parameters.

Some parameters may affect engine operation in ways a operator does not expect without adequate training. These may lead to power or performance complaints, even when the engine is performing to specification.

Passwords

"System Configuration Parameters" are protected by factory passwords. Factory passwords are calculated on a computer system available only to Caterpillar dealers. Since factory passwords contain alphabetic characters, only the ECAP may change System Configuration Parameters. System Configuration Parameters affect horsepower family or emissions.

"Customer Parameters" are protected by customer passwords. The customer passwords are programmed by the customer.

See section 2.0 on "Programming 3176B Parameters", for more details when passwords are needed and how to obtain them.

Self-Diagnostics

The 3176B electronic system has some ability to diagnose itself. When a problem is detected, a diagnostic code is generated and the Diagnostic/Check Engine lamp is turned On. 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 of "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 do not necessarily mean something needs to be repaired. They are instead 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.

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.

Main Speed Sensor P-602

Engine Oil Pressure P-610

Engine Coolant Temperature P-607

Back-Up Speed Sensor P-603

Engine Boost Pressure P-611

Engine Coolant Level P-613

Throttle P-504

Transmission Oil Pressure P-515

Transmission Oil Temperature P-516

System Fault ... Use an ECAP to further diagnose the problem

For more information on the CMS, refer to 3176B Marine Engine Operation and Maintenance Manual.

Diagnostic Warning Outputs

The electronic control system provides six different warning lamps to warn the operator about engine and transmission conditions. These lamps can be used to obtain status of Low Oil Pressure, High Coolant Temperature, Low Coolant Level and Transmission Warning (High Oil Pressure and/or Temperature). A Diagnostic Lamp output and a Maintenance Indicator output are also provided. The diagnostic lamp uses flash codes to indicate the different diagnostic conditions present in the system. The maintenance indicator alerts the operator of the need for scheduled engine maintenance. The electronic control system provides three sinking and three sourcing drivers to indicate the various conditions. The three sinking drivers are capable of sinking 300 mAmp and the three sourcing drivers are capable of sourcing 300 mAmp. These diagnostic outputs can be used to drive a relay, buzzer or lamp. The diagram is an example of how to utilize the system warning outputs.

3176B EUI Electronic System

3176B Component Diagram

Electrical Connectors and Functions

Service Tools

The Caterpillar ECAP Service Tool for the 3176B Electronic Control system is designed to help the service technician analyze and locate faults or problems within the system. It is required to perform some sensor calibrations electronically, and to read or change engine parameters. The basic tool has small plug-in modules, called Service Program Modules (SPM), to adapt the basic tool to the specific Caterpillar electronic control application.

The Electronic Control Analyzer Programmer (ECAP) communicates with the 3176B Electronic Control Module to read Diagnostic Codes, to read the various sensor output signals such as engine rpm, or boost pressure, and controls electronic calibration of the 3176B sensors through the ECM.

The ECAP (requires PWM adapter to measure at the sensor) can measure Pulse Width Modulated (PWM) signals, such as the signal produced by the Throttle Position Sensor. The ECAP is required when entering Factory Passwords.

There are several adapter cables, breakout "T" cables, probes, etc., that are used with the service tools in order to gain access for measurements of wires carrying voltages and signals. Both heavy duty multimeter and the standard duty multimeter are suitable for making the necessary measurements. Other Special Tools include those needed to measure pressure or temperature.