Caterpillar Inc.

George Lin

Gurpreet Gambhir

Zenebe Gete

An onboard cooling system diagnostic strategy utilizes at least one temperature sensor fluidly positioned between an electronically controlled engine and a thermostat. The diagnostic algorithm operates by monitoring coolant temperature during engine startup. By comparing the actual coolant temperature during engine start-up to a predicted coolant temperature that should occur if no cooling system error is present, a cooling system fault condition may be identified. If a cooling system fault is detected, the diagnostic logic may activate the engine cooling fan or intrusively open an electrically controlled thermostat while monitoring the coolant temperature response to the intrusive action. If there is a substantial change in coolant temperature responsive to the intrusive action, this phenomenon can be utilized to correctly distinguish between a thermostat failure and a vehicle configuration error corresponding to an overcooled vehicle. The present disclosure also can utilize a similar strategy to diagnose problems associated with other vehicle fluid coolers that exchange heat with ambient air moved by a circulation fan.

Engine cooling system onboard diagnostic strategy

An exhaust system is provided having an exhaust path configured to direct an exhaust stream away from an engine. The system may also include an exhaust treatment device in the exhaust path and configured to act on one or more substances in the exhaust stream. Further, the system may include at least one temperature sensing device configured to provide an output indicative of a temperature at one or more locations on a working material of the exhaust treatment device. In addition, the system may include a controller configured to generate a temperature map of the working material of the exhaust treatment device and to determine deviations from an expected temperature map.

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Dunlap, IL, United States of America

George Lin