Engine System, Diesel 228Service Manual – CS7000
Over Temperature Shutdown
Here is how the engine over temperature shutdown works. To monitor engine temperature, the main
machine controller sends a voltage through an internal resistor out connector J7 pin number 5 on the green
wire with a yellow stripe to the engine coolant temperature switch. The switch is normally open. When the
engine overheats the switch closes. The closing of the switch connects the voltage source to ground which
drops the voltage seen by the main machine controller to nearly 0 volts. An engine temperature fault occurs
when the coolant sensor switches to ground. This fault will be displayed on the Control panel. In response to
the overheat condition, the main machine controller waits ve seconds to give the operator time to park the
machine then removes the power supply going out connector J3 pin number 9 from the APECS 3000
Governor controller, which causes the engine to shut down.
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