Patent ID: 6321695
Filing Date: 2001-11-27
Classification: F01P,F02D,Y02T

Abstract:
A method for diagnosing the operation of a cooling system including a coolant temperature sensor and a thermostat for controlling coolant flow between an engine and a radiator so as to regulate the temperature of engine coolant to a desired regulating value, the method comprising the steps of:initially comparing the sensed coolant temperature to a measure of ambient air temperature at an initiation of engine operation;modeling the coolant temperature independent of the coolant temperature sensor, assuming proper operation of the thermostat;determining when the modeled coolant temperature is indicative of a fully warmed up condition of the engine;subsequently comparing the sensed coolant temperature to said desired regulating value when it is determined that the modeled coolant temperature indicative of a fully warmed up condition of the engine; anddiagnosing the operation of the coolant temperature sensor and the thermostat based on the initial and subsequent comparisons.