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| Illustration 1 | g00495871 |
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(1) Crankshaft position sensor
(2) Camshaft position sensor (3) Inlet manifold pressure sensor (4) Electronic unit injector connector P300/J300 (5) Fuel temperature sensor (6) Inlet air temperature sensor (7) Atmospheric pressure sensor connector P203/J203 (8) Ground points for the OEM (9) Electronic Control Module (ECM) (10) ECM connector that is for the OEM (11) Atmospheric pressure sensor (12) ECM connector that is for the engine | |
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| Illustration 2 | g00495874 |
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(13) Coolant temperature sensor P100/J100
(14) Oil pressure sensor connector P201/J201 | |
The electronic control system includes Engine Monitoring. The system monitors information about the following items: engine oil pressure, coolant temperature, inlet manifold air temperature and coolant level. All truck engines are shipped from the factory with the following sensors: oil pressure sensor, coolant temperature sensor and inlet manifold air temperature. The vehicle manufacturer is responsible for providing and for installing the coolant level sensor. The coolant level sensor is the only sensor that can be individually selected for Engine Monitoring. The ECM Customer Programmable Parameter enables the coolant level sensor. The default factory setting is "NO". The ECM Customer Programmable Parameters have four levels that are for Engine Monitoring:
- Off Mode
- Warning Mode (Factory Default)
- Derate Mode
- Shutdown Mode
The ECM will ignore the oil pressure sensor and the coolant level sensor. Coolant Temperature is still used for Cold Mode. Inlet Manifold Air Temperature is used for operation in cold air regardless of the engine monitoring mode.
Warning mode uses the following sensors: Oil Pressure, Coolant Temperature, Inlet Manifold Temperature and Optional Coolant Level Sensor. Table 1 indicates the diagnostic codes that are available. The table also shows the effect on engine performance when the diagnostic code is active. When a diagnostic code is active, the Check Engine Lamp will flash and the Warning Lamp will come on.
| PID-FMI | Description of the Diagnostic Code | Warning Lamp | Derate |
| 100-01 | Low Oil Pressure Warning | SOLID | NONE |
| 100-11 | Very Low Oil Pressure Warning | SOLID | NONE |
| 105-00 | High Inlet Manifold Air Temperature Warning | SOLID | NONE |
| 105-11 | Very High Inlet Manifold Air Temperature Warning | SOLID | NONE |
| 110-00 | High Coolant Temperature Warning | SOLID | NONE |
| 110-11 | Very High Coolant Temperature | SOLID | NONE |
| 111-01 | Low Coolant Level Warning | SOLID | NONE |
| 111-11 | Very Low Coolant Level | SOLID | NONE |
Derate mode and Shutdown mode allows the ECM to alter engine performance. Derate mode and Shutdown mode helps the engine avoid damage. The engine should return to normal conditions. When the engine is derated, the Check Engine Lamp and the Warning Lamp will flash. Refer to Table 2. In the Derate column, MPH indicates that the vehicle speed is derated. The maximum derate is 45 mph. HP indicates that the engine horsepower is limited. The maximum derate is 160 hp. RPM indicates that the engine speed is limited. The maximum derate is 1350 rpm. For the operating conditions that cause these codes, refer to the appropriate section for the sensor.
| PID-FMI | Description of the Diagnostic Code | Warning Lamp | Derate |
| 100-01 | Low Oil Pressure Warning | SOLID | NONE |
| 100-11 | Very Low Oil Pressure Warning | FLASH | MPH, HP, RPM |
| 105-00 | High Inlet Manifold Air Temperature Warning | SOLID | NONE |
| 105-11 | Very High Inlet Manifold Air Temperature Warning | SOLID | NONE |
| 110-00 | High Coolant Temperature Warning | FLASH | MPH, HP |
| 110-11 | Very High Coolant Temperature | FLASH | MPH, HP |
| 111-01 | Low Coolant Level Warning | SOLID | NONE |
| 111-11 | Very Low Coolant Level | FLASH | MPH, HP |
Table 3 indicates the active diagnostic codes that are capable of shutting down the engine when the ECM is programmed to Shutdown. The "Time To Shutdown" column indicates the length of time until engine shutdown will occur. The engine must have been running for at least thirty seconds. "Start/Restart Time" is the amount of operation time before shutdown after the engine monitoring has just caused a shutdown. "NO" in the column indicates that the code will not cause engine shutdown.
| PID-FMI | Description of the Diagnostic Code | Time To Shutdown | Start and Restart Time |
| 100-01 | Low Oil Pressure Warning | NO | NO |
| 100-11 | Very Low Oil Pressure Warning | 30 sec | 18 sec |
| 105-00 | High Inlet Manifold Air Temperature Warning | NO | NO |
| 105-11 | Very High Inlet Manifold Air Temperature Warning | NO | NO |
| 110-00 | High Coolant Temperature Warning | NO | NO |
| 110-11 | Very High Coolant Temperature | 20 sec | 60 sec |
| 111-01 | Low Coolant Level Warning | NO | NO |
| 111-11 | Very Low Coolant Level | 30 sec | 80 sec |
Electronic Control System Operation
The electronic control system is integrally designed into the fuel system and into the air inlet system. The fuel delivery and injection timing are electronically controlled. In comparison to engines that are controlled mechanically, the electronic control system provides increased control of timing and increased control to the fuel to air ratio. Injection timing is achieved by precise control of injector firing time, and engine power is controlled by adjusting the firing duration. The ECM energizes the solenoid for the fuel injection pump in order to start the injection of fuel. The ECM will de-energize the solenoid for the fuel injection pump in order to stop the injection of fuel. Refer to the Systems Operation, Testing and Adjusting, "Fuel System" for a complete explanation of the fuel injection process.
The engine uses the following types of electronic components: input, control and output.
An input component is one that sends an electrical signal to the ECM. The signal that is sent varies in either voltage or in frequency when there is a change in some specific system of the vehicle. An example would be the engine speed/timing sensor or the coolant temperature sensor. The electronic control module recognizes the input sensor signal as information about the condition, environment, or operation of the vehicle.
An electronic control system component receives the input signals. Electronic circuits that are inside the ECM evaluate the signals. The ECM then supplies electrical energy to the output components of the system, which are in response to predetermined combinations of input signal values.
An output component is one that is operated by the ECM. An output component receives electrical energy from the ECM. The electrical energy is used to perform one of the following functions:
- Perform work. An example would be moving a solenoid plunger. An output component takes an active part in regulating or operating the vehicle.
- Give information or a warning. An example would be a light or an alarm to the operator of the vehicle.
The output components control the engine in order to improve the performance of the engine. Also, the fuel consumption of the engine is minimized, and the emission levels of the engine are reduced. A brief description of the sensors that are used in the electronic control system follows.
The atmospheric pressure sensor is an absolute pressure sensor that measures crankcase pressure. Both the boost pressure and the oil pressure are communicated to the service tools and over the data link. The two pressures are calculated by subtracting the reading for the atmospheric pressure sensor. The atmospheric pressure sensor measures pressure from
The boost pressure sensor is an absolute pressure sensor that measures inlet manifold pressure. The difference between the inlet manifold pressure measurement and the pressure that is measured by the atmospheric pressure sensor is called the boost pressure. The information is communicated to the service tools and over the data link. The boost pressure sensor measures pressure from
The coolant level sensor is purchased by the OEM and the coolant level sensor is installed by the OEM. The coolant level sensor is the only optional sensor. The coolant level sensor is selected through the ECM Customer Programmable Parameter. The ECM Customer Programmable Parameter is protected by Customer Passwords.
The engine coolant temperature is measured by an electronic sensor that is mounted on the water outlet housing. The signal from the coolant temperature sensor is used to modify the fuel mixture and the timing. This results in improved cold starting and improved cleanup of white smoke. The ECM supplies the coolant temperature sensor with 5.0 ± 0.5 VDC. The output voltage of the sensor is from 0.5 VDC to 4.5 VDC. The output voltage of the sensor depends on the temperature of the engine coolant. The coolant temperature sensor is used to indicate cold mode operation. The coolant temperature sensor is also used for engine monitoring.
Coolant Temperature Engine Monitoring Operation
If engine monitoring is programmed to "Derate" or to "Shutdown", and the ECM begins to detect a diagnostic code, the check engine lamp will flash. The warning lamp will then flash when the associated diagnostic code is active. When the warning lamp flashes, the engine is in derate mode.
The fuel temperature is monitored in order to adjust the calculations for the fuel rate. The fuel temperature is also monitored for a power correction when the fuel temperatures exceed
Inlet air temperature is used for the cooling fan driver and for engine monitoring. The inlet air temperature sensor is used in order to warn the driver of an excessive inlet manifold air temperature. The inlet air temperature sensor will not cause an engine derate or an engine shutdown.
The inlet air temperature must exceed the temperatures that are indicated for thirty seconds before a diagnostic code is logged, following engine start-up. A diagnostic code for the high inlet manifold temperature is triggered at
The oil pressure sensor is an absolute pressure sensor that measures oil pressure in the gallery. The oil pressure is communicated over the data link and the oil pressure is displayed by the service tools. The ECM uses the sensor input only if the parameter for Engine Monitoring is programmed to "Warning", "Derate", or "Shutdown". The oil pressure sensor measures pressure from
Retarder Enable for the Compression Brake
If the engine is equipped with a compression brake, the operation of the compression brake is provided through the RETARDER enable output. The RETARDER enable status is determined by the ECM. In order to determine the RETARDER enable status, the following items are monitored by the ECM: dash switch for the compression brake, clutch switch, accelerator pedal position, cruise control switch and engine speed (rpm). Operation of the compression brake will be restricted under improper engine operating conditions. The following conditions must be met in order to enable the compression brake:
- The engine speed (rpm) is above 1000 rpm.
- The accelerator pedal is not depressed.
- The clutch pedal is not depressed.
- The cruise control switch is "off".
- The switch for the compression brake is energized.
Camshaft Position Sensor and Crankshaft Position Sensor
The camshaft position sensor and the crankshaft position sensor are used to determine both engine speed and fuel injection timing. The camshaft position sensor senses motion of the camshaft. The crankshaft position sensor senses motion of the crankshaft.
Accelerator Pedal Position Sensor
The accelerator pedal position sensor is an electronic sensor that is connected to the accelerator pedal. The accelerator pedal position sensor sends a Pulse Width Modulated Signal to the ECM.
The vehicle speed sensor is an electromagnetic pickup that measures vehicle speed. The sensor measures vehicle speed from the rotation of the gear teeth that are in the drive train of the vehicle.
Check Engine Lamp (Diagnostic Lamp)
The Check Engine Lamp is sometimes referred to as the Diagnostic Lamp. The check engine lamp is located on the dashboard of the vehicle. The check engine lamp can be used as a diagnostic lamp in order to communicate any problems with the operation of the electronic control system.
Note: The check engine lamp and the warning lamp are different. For more information about terminology for electronic components, refer to Systems Operation, "Glossary of Electronic Control Terms".
When a diagnostic code is detected by the ECM, the check engine lamp will turn ON. When a diagnostic code is detected by the ECM, the check engine lamp will blink at five second intervals. The check engine lamp should be ON and the check engine lamp should be flashing Diagnostic Code 55 whenever the START switch is turned ON but the engine is not running. This condition will test whether the lamp is operating correctly.
If the check engine lamp comes on and the check engine lamp stays on after the initial start-up, the system has detected a diagnostic code. The check engine lamp or service tools can be used to identify the diagnostic code.
The dash mounted Cruise Control Switches are used to interrogate the ECM for system status. With the cruise control switch in the OFF position, move the SET/RESUME switch to the RESUME position. The check engine lamp will begin to flash in order to indicate a two digit diagnostic code while the SET/RESUME switch is held in the RESUME position. The sequence of flashes represents the system diagnostic message. The first sequence of flashes adds up to the first digit of the diagnostic code. After a one second pause, a second sequence of flashes will occur. The second sequence of flashes represent the second digit of the diagnostic code. If necessary, additional diagnostic codes will follow after a three second pause. Additional diagnostic codes will be displayed in the same manner.
The Check Engine Lamp is also used to monitor the Idle Shutdown Timer. The check engine lamp will start to flash at a rapid rate 90 seconds before the programmed idle time is reached. If the clutch pedal indicates a change in position or the service brake pedal indicates a change in position during the final 90 seconds, the idle shutdown timer will be disabled. The idle shutdown timer will then reset.
The ECM power supply provides electrical power to all engine mounted sensors and actuators. Reverse voltage polarity protection and resistance to vehicle power system voltage swings or surges have been designed into the ECM. The ECM also monitors all input from the sensors. The ECM also provides the correct outputs in order to ensure desired engine operation.
The ECM contains memory in order to store customer specified parameters. The ECM also identifies a selected factory engine rating. The memory also contains a personality module identification code in order to prevent unauthorized tampering. The memory also contains an identification code in order to prevent switching of engine ratings and other pertinent manufacturing information.
The wiring harness provides communication or signal paths to the various sensors. A boost pressure sensor, the Data Link Connector, and the engine/vehicle connectors are examples. The ECM performs many functions. The ECM contains all of the engine performance and all of the certification information. Examples of this information follow.
- Engine timing
- Air/fuel ratio
- Rated fuel position control maps
Note: NOTE: The following parameters are customer specified parameters.
- Engine Power Rating
- Vehicle Identification Number
- "PTO Vehicle Speed Limit" (PTO VSL)
- "PTO Engine RPM Limit" (PTO RPM)
- "Low Gears Limit"
- "Intermediate Gears Limit"
- "Engine RPM At Vehicle Speed Limit" (Eng RPM At VSL)
- "Gear down Protection, Top Engine Limit" (TEL)
- "Vehicle Speed Limit" (VSL)
- "High Gear Turn On Speed" (HiGr On)
- "Low Cruise Control Set Limit" (LCC)
- "High Cruise Control Speed Set Limit" (HCC)
- "Retarder Coast/Latch"
- "Idle Shutdown Timer"
The customer specified parameters may be secured by customer passwords. An ECM may be programmed for all of the parameters or any combination of the parameters. For a brief explanation of each of the customer specified parameters, refer to the Operation and Maintenance Manual.
The ECM is programmed to run diagnostic tests on all inputs and outputs in order to separate a diagnostic code to a specific circuit. A diagnostic code can be displayed on the check engine lamp. A flashing check engine lamp represents a diagnostic code. A multimeter can be used to troubleshoot most problems. The ECM will also log most diagnostic codes that are generated during engine operation. The logged codes or the intermittent codes can be read by an electronic service tool.
The ECM provides a signal in order to disable the cooling fan. The output of the ECM is high for "fan off". The "cooling fan disable" signal is for "ON/OFF" control of the fan. The "ON/OFF" control is based on the following items: coolant temperature, operation of the engine brake, engine speed, intake manifold air temperature and an optional control that is based on an OEM installed high pressure switch for an air conditioner. All other control of the cooling fan is the responsibility of the OEM.
The ECM turns off the cooling fan driver while the engine is cranking. This prevents unnecessary cycling of the cooling fan. Because an electrical open circuit is the most likely failure mode, Caterpillar recommends a normally open relay for this circuit.