HARNESS AS- 4171876 - Caterpillar

Illustration 1 g01386787
(1) Control module (2) Manifold air pressure sensor (3) NOX sensor (4) Speed sensor (magnetic pickup) (5) Fuel valveControl Module
Illustration 2 g01417215
Control module (6) "POWER" indicator (7) "ALARM" indicator (8) Display (9) KeypadThe inlet manifold air pressure is a measure of engine load. The exhaust NOX level is a measure of the exhaust emissions. The engine speed is monitored by a speed sensor. The control uses the information from these inputs plus the target NOX settings in order to determine the desired emissions setpoint. The control uses the information from these inputs in order to maintain engine operation at that setpoint.The system is separate and independent from all of the other engine control systems. When the system is ON, "POWER" indicator (6) is illuminated. The engine can be run with the system in a manual mode or an automatic mode.If the system detects a diagnostic condition, "ALARM" indicator (7) is illuminated. If the system is operating in the manual mode, or if a diagnostic condition has been acknowledged, the "ALARM" indicator (7) blinks.Display (8) informs the operator of the status of the system. The manifold pressure and the level of the NOX sensor are continuously updated on the display in both the manual mode and the automatic mode. The NOX sensor must be active and ready. The mode is selected with keypad (9). The display and the keypad are the user interface for the air/fuel ratio control. The operator uses the display and the keypad for several functions. The display and the keypad are used for adjustment of the system parameters and for calibration of the NOX sensor.When the system is in the automatic mode, the control module moves the fuel valve in order to control the emissions. The automatic control is based on the closed loop feedback for the part per million (ppm) of NOX in the exhaust. The control adjusts the position of the fuel valve in order to maintain the desired exhaust NOX level. The fuel valve is adjusted according to the engine speed, the engine load, and the target NOX settings.When the system is in the manual mode, the fuel valve remains in a fixed position. The engine's exhaust emissions can change as the load, the speed, or the ambient conditions change. The manual mode can be useful for adjusting the system and for investigating diagnostics. The manual mode can also be used in case of a problem with a sensor.Manifold Air Pressure Sensor
The manifold air pressure sensor is mounted in the engine's air inlet manifold. The sensor measures the engine's absolute inlet manifold air pressure. The control uses the information to calculate the engine load. The three-wire sensor has a pulse width modulated signal (PWM) with a width of 500 HZ. The duty cycle is measured by the control and the signal is displayed in absolute kPa.NOX Sensor
The NOx sensor is mounted above the exhaust elbow. The sensor indicates the concentration of NOx in the engine's exhaust. The sensor incorporates a heater and