BI620123
Service Manual
SWITCHES There are two on/off switch inputs to the electronic shutdown system for the starting and running of the system the start/restart and the engine start. These switches also have 470 ohm resistors in series in the lines. The start/restart switch powers up the electronic shutdown system (but does not switch power directly). The engine start switch closes when the air driven starter is activated (it does not have to stay closed). Its purpose is to start the inhibit timer that prevents the oil pressure and coolant circulation sensors from shutting the engine for some 25 seconds after start. If this switch were not to close, the engine would start and run ignoring the oil pressure and coolant circulation sensors. The start fault LED comes on when the oil pressure becomes normal and the start engine switch has not been closed. In that condition, if there is an oil pressure loss while running, the engine will shutdown after the oil pressure is lost. The start fault display LED is an important indicator of possible trouble in the future. SENSORS The sensors are mechanical or electronic switches with 470 ohm resistor in series. If the switch is closed (and the resistance through the line is 470 ohm), the sensor is signalling normal condition. If the switch is open (and the resistance through the line is infinity), the sensor is signalling alarm, or the wire is broken. If the resistance through the line is closed to short circuit, the wire is damaged. SENSOR LOCATIONS Engine Coolant Level Sensor The engine coolant level sensor is located in the engine make up tank adjacent to the engine. This sensor monitors the engine coolant level and will shut the machine down by stopping power to the solenoid valve. This valve will open exhausting air pressure from the system thus the fuel shutdown cylinder will close the fuel rack. This closes of fuel to the engine and shuts the engine down. There is no need for routine calibration of the coolant level sensor as long as routine testing is carried out daily.
Engine Coolant Level Sensor
Rev. 0
FBL 10 LHD/Utility Serial No. 80042
247
