A method and a diagnostic system for detecting faults or for warning a vehicle operator of a fault in an air intake heating system for supplying heated air to a vehicle internal combustion engine, an air intake heating and diagnostic system for use with a vehicle having an internal combustion engine and a method of controlling an air intake heating system for an internal combustion engine of a vehicle

摘要

An air intake heating and diagnostic system (10) for an internal combustion engine includes a microprocessor based controller (12) for activating electrical heating elements (26 and 28) for a preheat time period prior to starting the engine and for a postheat time period after starting the engine. The controller (12) receives inputs corresponding to intake manifold air temperature, battery temperature, vehicle speed, engine speed, and key switch position. The system (10) continuously monitors the integrity of the various sensors (14,16,18,20), monitors the functionality of the heating elements (26 and 28) during the postheat time period, and warns the vehicle operator by illuminating a "check engine" lamp (38) if certain fault conditions are detected. In both cases, the controller (12) sets fault flags within the controller memory (40) corresponding to the detected fault conditions.