Method and apparatus for detecting the operation of an engine-independent auxiliary heater and for diagnosing a coolant temperature of a motor vehicle

Abstract

A method and apparatus for detecting the operation of an engine-independent auxiliary heater in a cooling system with multiple coolant circuits in a vehicle system with an auxiliary heater. On or after activating the vehicle system for a cold start, a shut-off valve is opened between a first coolant circuit with the auxiliary heater and a second coolant circuit with the coolant temperature sensor. A coolant pump is activated so that coolant from the first coolant circuit flushes around the coolant temperature sensor. A time course of a temperature reading from the coolant temperature sensor is performed for a predetermined period of time from the time the vehicle system is activated. A gradient of the temperature reading curve is determined. The gradient of the temperature reading curve is evaluated using a threshold value comparison to determine whether the auxiliary heater was activated before the cold start.

Dependencies are inferred from the claim text.