CAB AR 2134510 - Caterpillar

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Engine monitoring circuitThe components of the engine monitoring circuit are the Engine Electronic Control Module (Engine ECM), the Caterpillar Monitoring System ECM, the gauge module, the coolant level sensor, the turbo inlet air pressure sensor, the atmospheric pressure sensor, the engine oil pressure sensor, and the engine coolant temperature sensor.
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Left side view of engine (1) Engine ECM
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Dash panel (2) Caterpillar Monitoring System ECM (behind display) (3) Engine oil pressure alert indicator (4) Air filter restriction alert indicator (5) Engine coolant level alert indicator
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Dash panel (6) Gauge module (7) Coolant temperature gauge
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View of radiator header tank (8) Coolant level sensor
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Left side view of machine (9) Turbo inlet air pressure sensor
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Right side view of engine (10) Atmospheric pressure sensor
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Right side view of engine (11) Engine oil pressure sensor
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Top view of engine (12) Engine coolant temperature sensorWith the key start switch in the ON position, 24 volt power is supplied from the batteries via circuit breaker #11 to the Engine ECM. The Engine ECM supplies 5 volt power to the turbo inlet air pressure sensor, the atmospheric pressure sensor, the engine oil pressure sensor, the engine coolant temperature sensor, and 8 volt power to the coolant level sensor.Coolant level sensor (8) sends a signal to Engine ECM (1) which indicates whether coolant fluid is at the correct level in the radiator header tank, if not the Engine ECM will record the fault. This fault is then sent to Caterpillar Monitoring System ECM (2) via the CAT Data Link. The Caterpillar Monitoring System ECM registers the fault and turns on engine coolant level alert indicator (5) .With the engine running, engine oil pressure sensor (11) and engine coolant temperature sensor (12) send continually changing voltage signals to the Engine ECM. The Engine ECM compares these signals with the changing engine requirements and monitors them within a normal range. The engine coolant temperature will be sent to gauge module (6) via the CAT Data Link. The coolant temperature will be displayed on coolant temperature gauge (7) .The Engine ECM monitors turbo inlet air pressure sensor (9). If the air filters become plugged, the Engine ECM sends a signal to the Caterpillar Monitoring System ECM via the CAT Data Link. Air filter restriction alert indicator (4) will be on.If the signal from the engine oil pressure sensor, the engine coolant temperature sensor, the turbo inlet air pressure sensor, the coolant level sensor or atmospheric pressure sensor (10) is out of range for the engines requirements, the Engine ECM will begin timing the conditions. The Engine ECM monitors the condition of the sensors and will derate the engine or shut the engine down depending on the severity of the conditions.Reference: For more information on the engine monitoring system, refer to Operation and Maintenance Manual, "Caterpillar Monitoring System" for the machine that is being serviced.