The control system consists of the following components:
- Engine Control Module (ECM)
- Software (flash file)
- Wiring
- Sensors
- Actuators
The following information provides a general description of the control system. Refer to the Systems Operation manual for detailed information about the control system.
Electronic Control Circuit Diagram
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| Illustration 1 | g01442386 |
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Electronic control circuit diagram | |
Illustration 2 is a block diagram of the control system for C13 engines. Illustration 3 is a block diagram of the control system for C15 engines.
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| Illustration 2 | g01384887 |
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Block diagram for C13 engines (1) Air cleaner (2) Inlet air temperature sensor (3) Control group for the Clean Gas Induction System (CGI) (4) CGI Cooler (5) Differential pressure sensor for the CGI system (6) Absolute pressure sensor for the CGI system (7) Temperature sensor for the CGI system (8) Turbocharger outlet temperature sensor (9) Flame detection temperature sensor (10) Flame boundary temperature sensor (11) Ignition coil (12) Spark plug (13) ARD head (14) ARD body (15) DPF (16) Inlet temperature sensor for the DPF (17) Differential pressure sensor for the DPF (18) Outlet temperature sensor for the DPF (19) Low pressure turbocharger (20) High pressure turbocharger (21) Optional precooler (22) Control group for the combustion air system (23) Differential pressure sensor for the combustion air supply (24) Filter for the purge air (25) ARD purge air pump (26) Pilot fuel pressure sensor (27) Main fuel pressure sensor (28) Pilot fuel control solenoid (29) Main fuel control solenoid (30) Fuel enable valve (31) Fuel pressure sensor (if equipped) (32) (33) Fuel transfer pump (34) Primary fuel filter (35) Fuel temperature sensor (36) Secondary fuel filter (37) Fuel tank (38) Intake valve actuation control valve (39) Intake valve actuation pressure sensor (40) Air-to-air aftercooler (41) Coolant temperature sensor (42) Secondary speed-timing sensor (camshaft) (43) Primary speed-timing sensor (crankshaft) (44) Fuel injectors (45) Intake valve actuators (46) Compression brakes (47) Crankcase pressure sensor (48) Intake manifold air temperature sensor (49) Intake manifold pressure sensor (50) Oil pressure sensor (51) ECM (52) Engine | |
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| Illustration 3 | g01384888 |
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Block diagram for C15 engines High horsepower engines have two diesel particulate filters (15). (1) Air cleaner (2) Inlet air temperature sensor (3) Control group for the Clean Gas Induction System (CGI) (4) CGI Cooler (5) Differential pressure sensor for the CGI system (6) Absolute pressure sensor for the CGI system (7) Temperature sensor for the CGI system (8) Turbocharger outlet temperature sensor (9) Flame detection temperature sensor (10) Flame boundary temperature sensor (11) Ignition coil (12) Spark plug (13) ARD head (14) ARD body (15) DPF (16) Inlet temperature sensor for the DPF (17) Differential pressure sensor for the DPF (18) Outlet temperature sensor for the DPF (19) Low pressure turbocharger (20) High pressure turbocharger (21) Optional precooler (22) Control group for the combustion air system (23) Differential pressure sensor for the combustion air supply (24) Filter for the purge air (25) ARD purge air pump (26) Pilot fuel pressure sensor (27) Main fuel pressure sensor (28) Pilot fuel control solenoid (29) Main fuel control solenoid (30) Fuel enable valve (31) Fuel pressure sensor (if equipped) (32) (33) Fuel transfer pump (34) Primary fuel filter (35) Fuel temperature sensor (36) Secondary fuel filter (37) Fuel tank (38) Intake valve actuation control valve (39) Intake valve actuation pressure sensor (40) Air-to-air aftercooler (41) Coolant temperature sensor (42) Secondary speed-timing sensor (camshaft) (43) Primary speed-timing sensor (crankshaft) (44) Fuel injectors (45) Intake valve actuators (46) Compression brakes (47) Crankcase pressure sensor (48) Intake manifold air temperature sensor (49) Intake manifold pressure sensor (50) Oil pressure sensor (51) ECM (52) Engine | |
The ECM governs the engine. The ECM determines the timing, the injection pressure, and the amount of fuel that is delivered to each cylinder. These factors are based on the actual conditions and on the desired conditions at any given time during starting and operation.
The governor uses the accelerator pedal position sensor to determine the desired engine speed. The governor compares the desired engine speed to the actual engine speed. The actual engine speed is determined through interpretation of the signals that are received by the ECM from the engine speed/timing sensors. If the desired engine speed is greater than the actual engine speed, the governor injects more fuel in order to increase engine speed.
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| Illustration 4 | g01120999 |
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Typical example | |
The desired engine speed is typically determined by one of the following conditions:
- The position of the accelerator pedal
- The desired vehicle speed in cruise control
- The desired engine speed in Power Take-Off (PTO)
Once the governor has determined the amount of fuel that is required, the governor must determine the timing of the fuel injection. Fuel injection timing is determined by the ECM after considering input from the following components:
- Coolant temperature sensor
- Intake manifold temperature sensor
- Intake manifold pressure sensor
- Atmospheric pressure
The ECM adjusts timing for optimum engine performance and for fuel economy. Actual timing and desired timing cannot be viewed with Caterpillar Electronic Technician (ET). The ECM determines the location of top center of the number one cylinder from the signals that are provided by the engine speed/timing sensors. The ECM determines when injection should occur relative to top center. The ECM then provides the signal to the injector at the desired time.
The ECM sends a high voltage signal to the injector solenoids in order to energize the solenoids. By controlling the timing and the duration of the high voltage signal, the ECM can control the following aspects of injection:
- Injection timing
- Fuel delivery
The flash file inside the ECM establishes certain limits on the amount of fuel that can be injected. The "FRC Fuel Limit" is a limit that is based on the intake manifold pressure. The "FRC Fuel Limit" is used to control the air/fuel ratio for control of emissions. When the ECM senses a higher intake manifold pressure, the ECM increases the "FRC Fuel Limit". A higher intake manifold pressure indicates that there is more air in the cylinder. When the ECM increases the "FRC Fuel Limit", the ECM changes the control signal to the injector in order to allow more fuel into the cylinder.
The "Rated Fuel Limit" is a limit that is based on the power rating of the engine and on the engine rpm. The "Rated Fuel Limit" is similar to the rack stops and the torque spring on a mechanically governed engine. The "Rated Fuel Limit" provides the power curves and the torque curves for a specific engine family and a specific engine rating. All of these limits are determined at the factory. These limits cannot be changed.
Customer Parameters and Engine Speed Governing
A unique feature with electronic engines is customer specified parameters. These parameters allow the vehicle owner to fine tune the ECM for engine operation. Fine tuning the ECM allows the vehicle owner to accommodate the typical usage of the vehicle and the power train of the vehicle.
Many of the customer parameters provide additional restrictions on the actions that will be performed by the ECM in response to the driver's input. The "PTO Top Engine Limit" is an engine rpm limit that is used by the ECM to limit the fuel during operation of the PTO. The ECM will not fuel the injectors above this rpm.
Some parameters are intended to notify the driver of potential engine damage (engine monitoring parameters). Some parameters enhance fuel economy (vehicle speed, cruise control, engine/gear speed limit parameter and idle shutdown). Other parameters are used to enhance the engine installation into the vehicle. Other parameters are used to provide engine operating information to the truck engine owner.
Other ECM Functions for Performance
The ECM also provides enhanced control of the engine for vehicle functions such as retarding the engine and controlling the cooling fan. Refer to Troubleshooting, "Configuration Parameters" for supplemental information about the systems that can be monitored by the ECM in order to provide enhanced vehicle performance, fuel economy and convenience for the driver.
The ECM maintains total data of the engine for the following parameters:
- "Total Time" (Engine Hours)
- "Total Distance"
- "PTO Time"
- "PTO Fuel"
- "Idle Time"
- "Idle Fuel"
- "Total Fuel"
- "Average Load Factor"
The "Total Time" is the engine's operating hours. The operating hours do not include the operating time when the ECM is powered but the engine is not running.
"Total Distance" data requires a vehicle speed sensor or an electronic vehicle speed source to be connected to the ECM. The same sensor is used for vehicle speed. Distance can be displayed in miles or kilometers.
"PTO Time" and "PTO Fuel" are logged when engine rpm is set with the cruise switches and the engine is operating under some load. Also, "PTO Time" and "PTO Fuel" are logged when the PTO On/Off switch is in the ON position and vehicle speed is within the range of the "PTO Vehicle Speed Limit" parameter.
"Idle Time" and "Idle Fuel" can include operating time when all of the following conditions are met:
- The engine speed is set by using the cruise switches and the vehicle speed is within the range of the "Idle Vehicle Speed Limit" parameter.
- The engine is not operating under a load.
Fuel information can be displayed in US gallons or in liters.
"Total Fuel" is the total amount of fuel that is consumed by the engine during operation.
"Total Max Fuel" is the maximum amount of fuel that could have been consumed by the engine during operation.
"Average Load Factor" provides relative engine operating information. "Average Load Factor" compares actual operating information of the engine to the maximum engine operation that is available. "Average Load Factor" is determined by using "Total Max Fuel", "Idle Fuel", and "Total Fuel". All of these parameters are available with Cat ET. These parameters are available within the menu for "Current Totals".
Trip Data That is Stored in the ECM
The trip data allows the tracking of engine operation by the vehicle owner over intervals that are defined by the vehicle owner. All of the trip data is stored in memory and the trip data is maintained through the unswitched battery lines when the ignition switch is OFF. An internal battery maintains this information while the unswitched battery lines are disconnected.
Fleet trip data includes histograms and custom data. The fleet trip data includes data for the following parameters:
- "Total Time (Engine Hours)"
- "Driving Time"
- "Distance"
- "Fuel"
- "Overall Fuel Economy"
- "Driving Fuel Economy"
- "Idle Time"
- "Idle Fuel"
- "Percent Idle Time"
- "PTO Time"
- "PTO Fuel"
- "Percent PTO Time"
- "Average Load Factor"
- "Average Vehicle Speed"
- "Average Driving Speed"
- "Maximum Vehicle Speed"
- "Maximum Engine Speed"
- "Start Time"
- "End Time"
- "Start Odometer"
- "End Odometer"
Fleet trip data includes a fleet trip segment, histograms, and custom data. The fleet trip segment records the same parameters as the driver trip segment except that the fleet trip segment can be reset independently of the driver trip segment.
Three histograms are available. One histogram records engine hours versus the engine speed. The second histogram records engine hours versus vehicle speed. The third histogram records engine hours versus engine speed and vehicle speed.
Cat ET calculates the percentage of time that is spent in each of the engine rpm or vehicle speed ranges. Custom data is available. Custom data allows the recording of engine parameters that are specified by the vehicle owner. The ECM records the custom data.
A reset of the fleet trip data which includes the fleet trip segment, the histograms, and the custom data can be done in several ways. The following tools can be used to reset the fleet trip data:
- Cat ET which may require customer passwords
- Caterpillar Fleet Information Software (FIS)
- Caterpillar Messenger driver information display
When the data is reset, the ECM records the current totals at the time of the reset. These totals are used as the starting point for the fleet trip. The following tools access the recorded starting point:
- Cat ET
- Caterpillar FIS
- Messenger
The tool then subtracts the recorded starting point from the current totals in the ECM in order to calculate the fleet trip data. Resetting the fleet trip data requires customer passwords if the passwords are programmed.
Fleet trip custom data is part of the fleet trip segment. Fleet trip custom data allows the owner of the vehicle to set five customized methods of recording data for the vehicle. Refer to Illustration 5 for the basic program.
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| Illustration 5 | g00628194 |
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Basic program | |
The following list defines the options for variable 1 of the basic program:
- "Engine Hours"
- "Distance Traveled"
- "Fuel Burned"
- "Occurrences"
Refer to the following list for information regarding the options that are available for variable 2 and variable 5.
Variables 3, 4, 6, and 7 define the minimum range and the maximum range of variables 2 and 5.
- Engine rpm
- Vehicle speed
- Fuel rate
- Load factor
- Coolant temperature
- Oil pressure
- Fuel temperature
- Intake manifold air temperature
- Cruise
- PTO
- Engine retarder
- Throttle position
- Brake
Refer to the example of a custom data program, as shown below.
“Fuel Burned when Fuel Temperature is from
The custom data programs are protected by customer passwords. The programs are stored in permanent memory. The programs are not reset when the fleet trip segment is reset, but the data that is recorded for the trip is reset.
A customer parameter is available in order to record a quick stop event. The parameter determines the rate of change in vehicle speed that is used by the ECM in order to record a quick stop event code and a quick stop snapshot. Refer to Troubleshooting, "Diagnostic Capabilities".
The ECM records the current totals when a reset occurs for the following three levels of maintenance:
- PM1
- PM2
- Cooling system clean/flush
The ECM uses the previous point of maintenance in order to calculate the timing of the next scheduled maintenance work.
The "Maintenance Indicator Mode" is programmable to "Hours" or to "Distance". The "PM1 Maintenance" is programmable to one of the following positions: "Off", "Automatic Distance", "Automatic Hours", "Manual Distance" and "Manual Hours".
If the PM1 is programmed to the automatic mode, the ECM calculates the next point of maintenance by considering the history of the vehicle's operation from the previous maintenance interval. If the vehicle has a history of poor fuel economy the maintenance indicator parameter occurs sooner than a vehicle with better fuel economy.
The ECM also uses the engine oil capacity. A larger engine oil capacity provides a longer maintenance interval. The engine oil capacity is programmed into the ECM in liters or in quarts. If the PM1 is programmed to the manual mode, the owner can program the ECM with the owner's specific maintenance interval. The maintenance interval can be programmed to the owner's specific interval that is based on mileage or on time. The interval for the PM2 and the interval for the cooling system clean/flush are established by the factory.
Caterpillar Messenger is available to provide engine operating information to the driver. The "Fleet Trip Data", and the "Maintenance Indicator" data can be viewed. However, the fleet trip histograms and the custom data cannot be viewed from the display.
Messenger provides the ability to enter an ID code for a driver in order to divide the "Fleet Trip Data" for two drivers. If the driver enters the information regarding the state of travel, the "Fleet Trip Data" can be tagged by the state of travel.
Messenger can be used in order to tag portions of the "Fleet Trip Data" into two ID codes. Messenger can also be used in order to tag portions of the "Fleet Trip Data" into the state of travel. The ID code and the information regarding the state of travel cannot be viewed from the display. Only the Caterpillar FIS can view this information. The ability to reset any of these parameters is dependent on customer parameters in the ECM.
Messenger also displays operating information such as engine rpm, coolant temperature, intake manifold pressure, etc.
Messenger also displays engine diagnostic codes with the PID-FMI diagnostic codes. Messenger also displays a brief text description of the diagnostic codes.
An available feature on Messenger is the theft deterrent. The theft deterrent allows the driver to input a password prior to shutdown. The theft deterrent prevents the engine from restarting until the password is successfully entered. Messenger must have the version of software that is capable of supporting this feature.
An "Auto-Enable" option is available for the theft deterrent. If this option is selected, the theft deterrent is automatically activated when the engine is shut down. The correct password must be entered in order to start the engine.
"Secure Idle" is another theft deterrent. This allows the driver to bring the engine to an idle condition. The driver then enters the password. The engine will remain at low idle until the password is re-entered. If the engine is shutdown, a password is required to go above low idle after start-up.
Fleet Information Software (FIS)
The Caterpillar FIS is another method that can be used to review the trip information. The entire "Fleet Trip Segment", which includes the following elements of data can be accessed with the Caterpillar FIS:
- Histograms
- Custom data
- Information that is tagged by the ID code
- Information that is tagged by the state of travel
Maintenance indicator information can be retrieved with the Caterpillar FIS.
When the Caterpillar FIS downloads the information, the Caterpillar FIS also resets the ECM in order to prepare the ECM for the next trip.
Certain parameters that affect engine operation may be changed with Cat ET. The parameters are stored in the ECM, and the parameters 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. System configuration parameters affect emissions or power ratings within an engine family. Factory passwords must be obtained and factory passwords must be used to change the system configuration parameters.
Customer parameters are variable. Customer parameters can be used to affect the following characteristics of the engine within the limits that are set by the factory, by the monitoring system, and by PTO operation:
- Cruise control
- Vehicle speed limits
- Progressive shifting
- Rpm ratings
- Power ratings
Customer passwords may be required to change customer specified parameters.
Some of the parameters may affect engine operation in an unusual way. A driver might not expect this type of effect. Without adequate training, these parameters may lead to power complaints or performance complaints even though the engine's performance is to the specification.
Refer to Troubleshooting, "Configuration Parameters" for additional information on this subject.
System configuration parameters are protected by factory passwords. Factory passwords are calculated on a computer system that is available only to Caterpillar dealers. Since factory passwords contain alphabetic characters, only Cat ET may change system configuration parameters. System configuration parameters affect the power rating family or emissions.
Customer parameters can be protected by customer passwords. The customer passwords are programmed by the customer. Factory passwords can be used to change customer passwords if customer passwords are lost.
Refer to Troubleshooting, "Customer Passwords" and Troubleshooting, "Factory Passwords" for additional information on this subject.