C6.6 Industrial Engine Caterpillar

Introduction (Electronic Control System)

The Electronic Control Module (ECM) and the sensors are located on the left side of the engine. Refer to illustration 1.

Illustration 1	g01360052
(1) Coolant Temperature Sensor (2) Inlet Manifold Temperature Sensor (3) Inlet Manifold Pressure Sensor (4) Fuel Manifold Pressure Sensor (5) Electronic Control Module (ECM) (6) Oil Pressure Sensor (7) Primary Speed/Timing Sensor (8) Secondary Speed/Timing Sensor (9) Solenoid for the Fuel Injection Pump

Note: If equipped, the wastegate solenoid is installed on the right side of the engine.

Illustration 2	g01360078

The C6.6 engine was designed for electronic control. The engine has an Electronic Control Module (ECM), a fuel injection pump and electronic unit injectors. All of these items are electronically controlled. There are also a number of engine sensors. Turbocharged engines can be equipped with an electronically controlled wastegate for the turbocharger. The ECM controls the engine operating parameters through the software within the ECM and the inputs from the various sensors. The software contains parameters that control the engine operation. The parameters include all of the operating maps and customer selected parameters.

Illustration 3	g01178531

The electronic control system has the following components:

• ECM

• Pressure sensors

• Temperature Sensors

• Crankshaft position sensor

• Secondary position sensor

• The solenoid for the fuel injection pump

• Wastegate solenoid

• Electronic unit injectors

ECM

Illustration 4	g01199973
ECM

The Electronic Control Module (ECM) (1) functions as a governor and a computer for the fuel system. The ECM receives signals from the sensors in order to control the timing and the engine speed.

The electronic system consists of the ECM, the engine sensors and inputs from the parent machine. The ECM is the computer. The personality module is the software for the computer. The personality module contains the operating maps. The operating maps define the following characteristics of the engine:

• Engine power

• Torque curves

• Engine speed (rpm)

• Engine Noise

• Smoke and Emissions

The factory passwords restrict changes to authorized personnel. Factory passwords are required to clear any event code. Refer to the Troubleshooting Guide, "Factory Passwords" For more information on the passwords.

The ECM has an excellent record of reliability. Any problems in the system are most likely to be the connectors and the wiring harness. The ECM should be the last item in troubleshooting the engine.

The programmable software contains all the fuel setting information. The information determines the engine performance.

Flash programming is the method of programming or updating the programmable software. Refer to the Troubleshooting Guide, "Flashing Programming " for the instructions on the flash programming of the programmable software.

The ECM is sealed and the ECM needs no routine adjustment or maintenance.

Engine Speed Governor

The electronic controls determine the injection timing, the amount of fuel that is delivered to the cylinders and the intake manifold pressure if an electronically controlled wastegate is installed on the turbocharger. These decisions are based on the actual conditions and the desired conditions at any given time.

The governor has software that compares the desired engine speed to the actual engine speed. The actual engine speed is determined through the primary speed/timing sensor and the secondary speed/timing sensor. If the desired engine speed is greater than the actual engine speed, the governor injects more fuel in order to increase engine speed.

Timing Considerations

Once the governor has determined the amount of fuel that is required, the software must determine the timing of the fuel injection. Fuel injection timing is determined by the ECM after considering input from the following components:

• Engine coolant temperature sensor

• The sensor for the intake manifold air temperature

• The sensor for the intake manifold pressure

At start-up, the ECM determines the top center position of the number 1 cylinder from the secondary speed/timing sensor in the fuel injection pump. The ECM decides when fuel injection should occur relative to the top center position. The ECM optimizes engine performance by control of each of the electronic unit injectors so that the required amount of fuel is injected at the precise point of the engine's cycle. The electronic unit injectors are supplied high pressure fuel from the fuel manifold. The ECM also provides the signal to the solenoid in the fuel injection pump. The solenoid in the fuel injection pump controls a valve in the fuel injection pump. This valve controls the pressure in the fuel manifold. Fuel that is not required for the engine is diverted away from the fuel injection pump back to the fuel tank.

The ECM adjusts injection timing and fuel pressure for the best engine performance, the best fuel economy and the best control of exhaust emissions. The actual timing can be viewed with an electronic service tool. Also, the desired timing can be viewed with an electronic service tool.

Fuel Injection

The programmable software inside the ECM sets certain limits on the amount of fuel that can be injected.

The FRC Limit is a limit that is based on intake manifold air pressure and engine rpm. The FRC Limit is used to control the air/fuel ratio in order to control the engine's exhaust emissions. When the ECM senses a higher intake manifold air pressure, the ECM increases the FRC Limit. A higher intake manifold air pressure indicates that there is more air in the cylinder. When the ECM increases the FRC Limit, the ECM allows 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 enables the engine power and torque outputs to conform to the power and torque curves of a specific engine model.

These limits are in the programmable software and these limits cannot be changed.

Diagnostic Codes

When the ECM detects an electronic system problem, the ECM generates a diagnostic code. Also, the ECM logs the diagnostic code in order to indicate the time of the problem's occurrence. The ECM also logs the number of occurrences of the problem. Diagnostic codes are provided in order to indicate that the ECM has detected an electrical problem or an electronic problem with the engine control system. In some cases, the engine performance can be affected when the condition that is causing the code exists.

If the operator indicates that a performance problem occurs, the diagnostic code may indicate the cause of the problem. Use a laptop computer to access the diagnostic codes. The problem should then be corrected.

Event Codes

Event Codes are used to indicate that the ECM has detected an abnormal engine operating condition. The ECM will log the occurrence of the event code. This does not indicate an electrical malfunction or an electronic malfunction. If the temperature of the coolant in the engine is higher than the permitted limit, then the ECM will detect the condition. The ECM will then log an event code for the condition.

Passwords

System Configuration Parameters are protected by factory passwords. This will prevent unauthorized reprogramming of the system and the unauthorized removal of logged events. Factory passwords are calculated on a computer system that is available only to Caterpillar distributors. Since factory passwords contain alphabetic characters, only an electronic service tool may change System Configuration Parameters. System Configuration Parameters affect the power rating or the emissions. Passwords also allow the customer to control certain programmable engine parameters.

Refer to Troubleshooting, "Programming Parameters" and Troubleshooting, "Factory Passwords".

Speed/Timing Sensor

Illustration 5	g01334468
Timing wheel on the crankshaft

The primary engine position is a passive sensor. The timing wheel is located on the crankshaft. The speed/timing sensor receives a signal from the teeth on timing wheel. The extra space on the timing wheel gives one revolution per space. The space is oriented so that the space is 40 degrees after top center.

Illustration 6	g01336359
Schematic for speed/timing sensor

When the engine is cranking, the ECM uses the signal from the speed/timing sensor in the fuel injection pump. When the engine is running the ECM uses the signal from the speed/timing sensor on the crankshaft. This speed/timing sensor is the primary source of the engine position.

Pressure Sensors

Illustration 7	g01334496
Schematic for pressure sensors

The boost pressure sensor and the engine oil pressure sensor are active sensors.

The boost pressure sensor provides the ECM with a measurement of inlet manifold pressure in order to control the air/fuel ratio. This will reduce the engine smoke during transient conditions.

The operating range of the boost pressure sensors

For standard power engines,
the range is up to the following. ... 339 kPa (49.169 psi)

For all high power engine,
the range is up to the following. ... 440 kPa (63.818 psi)

The engine oil pressure sensor provides the ECM with a measurement of engine oil pressure. The ECM can warn the operator of possible conditions that can damage the engine. This includes the detection of an oil filter that is blocked.

The operating range for the engine oil pressure sensor ... 55 kPa to 339 kPa (8 psi to 50 psi)

Temperature Sensors

Illustration 8	g01334497
Schematic for the temperature sensors

The air inlet temperature sensor and the coolant temperature sensor are passive sensors. Each sensor provides a temperature input to the ECM. The ECM controls following operations:

• Fuel delivery

• Injection timing

The operating range for the sensors ... -40 °C to 150 °C (-40 °F to 302 °F)

The sensors are also used for engine monitoring.