0336909 JOHNSON SPACER, Screw, exh. hsg.

Engine And Pump Control System Block DiagramThe engine and pump control system continuously monitors and adjusts the engine speed and the hydraulic pump based on machine conditions and operator selections. The control system consists of the engine and pump control (controller), a monitor panel, various switches, sensors, relays, solenoids, lamps and alarms.The controller communicates with the monitor panel via a data link. The monitor panel provides the following machine system information for the operator and/or service person: warns of the occurrence of problem(s), shows the condition and provides diagnostic and adjustment information. The monitor panel is also used by the operator to select machine operational functions like: power mode, wiper mode, travel speed, etc.).Components Description
The same controller operates on different hydraulic excavators. All of the following components may not be present on every machine. The controller (with configuration software) recognizes the machine on which it is installed and therefore knows which components are present. For the location of components, see the Component Location chart on the Electrical System Schematic in the machine service manual for the machine being serviced.Engine And Pump Control (Controller)
Engine And Pump Control
(1) Controller. (2) Connector A. (3) Connector B. Electronic circuits within the controller make decisions to change the engine speed and the hydraulic pump outputs by controlling the governor actuator and the proportional reducing valve. The controller inputs and outputs are connected to the machine harness wiring through two connectors, one with 24 contacts and one with 40 contacts.Input/Output
The data link is bidirectional, allowing the controller to receive and send information. The purpose of the data link is to communicate with the monitor panel. The data link is not a visible component. It consists of internal control circuits and the connecting harness wiring.The controller sends information like; fuel level, engine coolant temperature and power mode selected to the monitor panel. The controller also receives operator request information from the monitor panel like; power mode and wiper mode selection.Inputs
The inputs describe the status of the machine systems. Two types of inputs exist; switch type and sensor type. Switches and harness wiring provide an open (floating) or ground to the switch inputs of the controller. Sensors (frequency, PWM or voltage) and harness wiring provide a changing signal to the sensor inputs of the controller.Switch Input - Key Start
The key start switch input (connector contact A-13) provides input about the key start switch. When the key start switch is ON this input is at +battery.Switch Inputs - Operational
The operational switch inputs (connector contacts A-19, A-20, A-28, A-29, A-36, A-37, A-38, A-39, B-15, B-17, B-18 and B-19) provide information about operator requests and machine systems. The status of the inputs (grounded, open or +battery) tell the system conditions (normal or abnormal). These inputs receive information from switches located within the machine systems (pressure and temperature) and operator input switches (low idle and engine speed dial).Switch Inputs - Harness Code
The harness code inputs (connector contacts A-12, A-22, A-32 and A-33) are used to tell the controller which machine model it is installed on. This information is necessary because of the differences in machine models. Engine size, idle speed, hydraulic pump type and other machine information is necessary for the controller to make decisions. The combination of grounded or open harness code inputs determine the harness code for each model. See the troubleshooting procedure E41 in the Testing And Adjusting section.Sensor Input - Frequency
At the frequency sensor input (connector contact B-6), an AC signal is present to represent the speed of a machine system. The engine speed frequency sensor provides an AC signal to the controller. The controller measures the frequency (Hz) of the AC signals. The resulting speed is used by the controller to make decisions.Sensor Input - Alternator
At the alternator sensor input (connector contact B-3), a square wave signal is present to represent the speed of the alternator. The controller measures the frequency (Hz) of the square wave signal. The controller uses this information to make decisions and to monitor the alternator output. When an abnormal condition exists the controller alerts the operator.Sensor Inputs - PWM
At each PWM sensor input (connector contacts B-21, B-23 and B-24), a PWM signal is present which represents the condition of a machine system. Temperature and position are examples of the conditions which are monitored. PWM sensors provide this information. The controller measures the duty cycle of the PWM signal, which represents the measured information. The controller uses this information to make decisions and to monitor machine systems. When an abnormal condition exists the controller alerts the operator.Sensor Inputs - Voltage
At the voltage sensor inputs (connector contacts B-9, B-10 and B-22), a voltage is present which represents the condition of a machine system. Level is an example of a condition which is monitored. Analog sensors or senders provide this information. The controller measures the voltage, which represents the measured information. The controller uses this information to make decisions and to monitor machine systems. When an abnormal condition exists the controller alerts the operator.Outputs
The controller responds to decisions by sending electrical signals through the various outputs. The outputs either create an action or provide information. In addition to the outputs listed in the Connector Contact Description Charts, the three status indicators inside the controller and the monitor panel are outputs of the controller. The monitor panel shows the operating status of the engine and pump control system and diagnostic information.The solenoid outputs (connector contacts A-6 through A-9, A-14, A-24 through A-27, A-35, B-1, B-2, B-13 and B-14), make it possible for the controller to cause action. This could be energizing a solenoid, sounding an alarm or activating a motor.Switches
Governor Backup Switch
Governor Backup SwitchThe purpose of