BUSHING 9R3700 - Caterpillar

The engine has an electronic control system.The control system consists of the following components:
Electronic Control Module (ECM)
Software (flash file)
Wiring
Sensors
ActuatorsThe following information provides a general description of the control system. Refer to Systems Operation, Testing, and Adjusting for detailed information about the control system.Electronic Control Circuit Diagram
Illustration 1 g03570461
Electronic control circuit diagram for the C4.4 engine with an EMCP 4.2 control panel
Illustration 2 g03573496
Electronic control circuit diagram for the C4.4 engine with an MCS control panelBlock Diagram
Refer to Illustration 3 for a block diagram of the control system.
Illustration 3 g03573658
Block diagram for the engine (1) Air cleaner (2) Air inlet temperature sensor (3) Exhaust gas temperature sensor (if equipped) (4) Turbocharger (5) Air-to-air aftercooler (6) Engine (7) Coolant temperature sensor (8) Primary speed/timing sensor (9) Fuel injectors (10) Return fuel cooler (11) Sea water pressure sensor (if equipped) (12) Return fuel pressure relief valve (13) Secondary speed/timing sensor (14) High-pressure fuel pump/transfer pump/fuel temperature sensor (15) Fuel rail pressure sensor (16) Pre-filter oil pressure sensor (if equipped) (17) Post filter oil pressure sensor (18) Coolant pressure sensor (19) Oil temperature sensor (if equipped) (20) Fuel leakage detection sensor (if equipped) (21) ECM (22) Electric fuel lift pump (23) Post-primary fuel filter pressure sensor (24) Pre-primary fuel filter pressure sensor (25) Primary fuel filter (26) Intake manifold pressure sensor (27) Intake manifold air temperature sensor (28) Transfer pump inlet regulator (29) Secondary fuel filter (30) Fuel tank (31) Post-secondary fuel filter pressure sensor (32) Pre-secondary fuel filter pressure sensorSystem Operation
Engine Governor
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 throttle signal 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.
Illustration 4 g02414657
Engine speed controlTiming Considerations
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 air temperature sensor
Intake manifold pressure sensorThe ECM adjusts timing for optimum engine performance and for economic fuel usage. Actual timing and desired timing cannot be viewed with the electronic service tool. 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 the top center position. The ECM then provides the signal to the injector at the desired time.Fuel Injection
The ECM sends a high voltage signal to the injector solenoids in order to energize the