Susan G Aldridge

US Patent:

20020193921, Dec 19, 2002

Filed:

Apr 8, 2002

Appl. No.:

10/118505

Inventors:

Ronald Reese - Goodrich MI, US
Gary Pallach - Chesterfield MI, US
Gary Dawson - Rochester MI, US
David Ploucha - Ann Arbor MI, US
Susan Aldridge - Linden MI, US

International Classification:

G06F017/00

US Classification:

701/029000, 701/001000

Abstract:

A method is provided for testing a thermostat in a motor vehicle. The method includes an engine warm-up model and a thermostat diagnostic. The engine warm-up model predicts the temperature that the engine coolant temperature should be equal to at a given time after start-up. This is based on the engine coolant temperature at start-up, ambient air temperature, and how the vehicle is driven subsequent to start-up. This predicted engine coolant temperature is compared to the actual engine coolant temperature as read by an engine coolant temperature sensor. The error between the predicted engine coolant temperature and the actual engine coolant temperature is calculated and integrated over time. The thermostat diagnostic runs at a pre-selected temperature after start-up and compares the integrated error to a predetermined threshold value. Depending upon the results of the comparison, a pass, fail, or inconclusive condition is determined.