FITTING-37 DEG 6V4390 - Caterpillar

Coolant Temperature Input Circuit
The temperature of the engine coolant is measured by an electronic sensor. The sensor is mounted on the cover of the regulator housing. The signal from the sensor is used to modify the fueling of the engine. The signal is also used to modify the timing for an improved cold start and for reduction in white smoke. The ECM supplies the coolant temperature sensor with 5.0 0.5 VDC. The sensor's output voltage is 0.2 4.6 VDC. This depends on the temperature of the engine's coolant.Throttle Position Input Circuit
The throttle position is obtained from an electronic sensor that is connected to the throttle pedal. The 8.0 0.5 VDC operating voltage is provided to the sensor by the electronic control module (ECM).The output of the throttle position sensor is a constant frequency signal with voltage levels of 0 or 10 volts. The pulse width is not the frequency of the signal. The pulse width of the signal is dependent upon the arm rotation of the throttle position sensor. The pulse width is interpreted by the ECM as the throttle position. The minimum duty cycle is between 10 and 22 percent. The maximum duty cycle is between 44 and 52 percent. The ECM interprets the minimum duty cycle as 0 percent of the throttle position. The ECM interprets the maximum duty cycle as 100 percent of the throttle position.The throttle position sensor is integrally mounted to the throttle pedal assembly. The throttle position sensor rotates approximately 18 degrees from the low idle stop to the high idle stop on the pedal assembly. The electronic control system will automatically calibrate any of the deadband in the throttle pedal. This occurs as the pedal is actuated throughout the range of travel. Mechanical stops on the pedal assembly restrict the rotation of the throttle sensor. This helps prevent damage to the sensor. The mechanical stops eliminate the need to manually adjust the pedal stops.Injector Output Circuits
An electrical signal from the ECM controls each electronic unit injector (EUI). This electrical signal determines the fuel injection timing. The duration of the electrical signal determines the quantity of fuel that is injected. The signal allows precise control of the injectors.Atmospheric Pressure Input Circuit
Atmospheric pressure is monitored by the atmospheric pressure sensor. The sensor is located on the mounting bracket for the ECM. A 5.0 0.5 VDC supply voltage is provided by the ECM. The output of the atmospheric pressure sensor is a DC signal. This signal has a range from 0.2 volts to 4.8