Motor vehicle cooling system status indicator

An apparatus for monitoring a status of a motor vehicle engine cooling system comprising a coolant temperature sensor;

• a coolant pressure sensor;
• means for generating at least one of a pressure output signal and a temperature output signal, the signals respectively being representative of pressure and temperature of the coolant;
• means for indicating a coolant system fault condition when the pressure of the coolant falls below a coolant pressure limit in relation to the temperature of the coolant;
• and means for summing the temperature and pressure output signals and providing a combined output signal indicative of the combined effect of one of the output signals modified by the other of the output signals, the combined output signal being applied to energise the indicating means.

A method of monitoring a status of a motor vehicle engine cooling system including the steps of:

• a) sensing pressure and temperature of coolant in the cooling system and generating electrical input pressure and input temperature signals in response thereto respectively;
• b) feeding at least one of the input pressure and input temperature signals to a signal calibrating circuit;
• c) setting the calibrating circuit to calibrate a respective input signal at a set pressure and a set temperature;
• d) generating at least one of a calibrated pressure output signal and a calibrated temperature output signal, the calibrated signals respectively being representative of the sensed pressure and temperature;
• e) comparing the pressure and temperature output signals;
• and
• f) generating a compared output signal at least when the pressure of the coolant is below a coolant pressure limit in relation to the temperature of the coolant.

An apparatus for monitoring a status of a motor vehicle engine cooling system comprising:

• a) means for sensing pressure and temperature of coolant in the cooling system and generating electrical input pressure and input temperature signals in response thereto, respectively;
• b) means for feeding at least one of the input pressure and input temperature signals to a signal calibrating circuit;
• c) means for generating at least one of a calibrated pressure output signal and a calibrated temperature output signal, the calibrated signals respectively being representative of the sensed pressure and temperature;
• d) means for comparing the calibrated pressure and temperature output signals;
• and
• e) means for generating a compared output signal at least when the pressure of the coolant is below a coolant pressure limit in relation to the temperature of the coolant.

An apparatus for monitoring the status of a motor vehicle engine cooling system comprising:

• a) means for sensing the temperature of coolant in the cooling system and generating an electrical input temperature signal in response thereto;
• b) means for feeding the input temperature signal to a calibrating circuit to generate a calibrated temperature output signal representative of the sensed temperature;
• c) switch means for sensing the pressure of coolant in the cooling system and generating a first electrical input pressure signal when the pressure of the coolant is below a pressure value and a second electrical input pressure signal when the pressure of the coolant is above the pressure value, the pressure value being significantly above atmospheric and significantly below normal operating coolant pressure;
• d) means for generating a desired pressure output signal in response to a selected one of the first and second electrical input pressure signals;
• e) means for comparing the pressure and temperature output signals;
• and
• f) means for generating a compared output signal at least when there is a first electrical input pressure signal and the calibrated temperature output signal is representative of a temperature above a temperature limit.