YOKE 7D3696 - Caterpillar

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Pulse width modulated signal
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Typical PWM sensor
Pulse width modulated sensors produce a digital signal. The duty cycle of the digital signal varies as the condition changes, but the frequency remains constant.Engine Speed Sensor
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Magnetic pickup (MPU)
The magnetic pickup (MPU) sends a signal that represents the speed of the engine to the control board and the tachometer. The MPU is located on the engine flywheel housing. The MPU is a single-pole permanent magnetic generator that is made of wire coils around a permanent magnet pole piece. As the teeth of the flywheel ring gear go through the magnetic lines of flux around the pickup, an AC voltage is generated. Positive voltage - Generated when each tooth goes by the pole piece.Negative voltage - Generated when each space between the teeth goes by the pole piece.A control board counts the frequency of the speed signal. The control board determines the engine speed.Air Inlet Pressure Sensor
The air inlet pressure sensor gives the monitoring system a value for the air inlet pressure. A gauge displays the status of the pressure. The air inlet pressure sensor is a pulse width modulated sensor that continuously generates a PWM signal. The duty cycle of the PWM signal varies from 10 to 90% in proportion to the air inlet pressure. The sensor base frequency is constant at 500 150 Hz.Temperature Sensor
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Temperature sensor
(5) Sensor
(6) Connector Temperature sensor reacts to the temperature of fluids such as engine oil or engine coolant. The sensor receives operating power from the main display module (+8 VDC) or from the battery (+12 VDC). The temperature sensor sends a signal to a Machine ECM, which sends it to the Monitoring System. A Machine ECM measures the duty cycle of the sensor signal to determine the fluid temperature.Switches
Switches provide information (input) to the main display module. Switches are the following two state devices:Closed - The switch connects the control input to the ground.Open - The switch does not connect the control input. The input is floating.During normal operation, all switches are closed. When a condition exceeds the trip point of the switch, the switch opens. The open tells the main display module of the abnormal condition. The main display module goes into warning operation, notifying the operator of the abnormal condition.Key Start Switch
When the key start switch is in the ON position, electrical power from the batteries is supplied to the Electronic Control Modules (ECMs).
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Key start switch
Engine Coolant Temperature Switch
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Engine coolant temperature switch
The engine coolant temperature switch sends a B− signal to the control board when the coolant temperature exceeds the trip point of the switch. This signal causes the control board to perform an engine shutdown for a high water temperature fault. The switch is mounted in the water jacket usually near the front of the engine. The exact location depends on the engine model.The switch has normally open and normally closed contacts. Only the normally open contacts "A" and "B" are used. Contact "A" connects to the