Where under the hood of a 2000 Buick Park Avenue is thermometer?

There isn't a thermometer in the traditional sense (like a mercury thermometer) under the hood of a 2000 Buick Park Avenue, or any modern car for that matter. The engine temperature is monitored by a temperature sensor, which is an electronic device. This sensor is typically located in the engine block or cylinder head and sends a signal to the car's computer (PCM or ECM). The computer then uses this signal to display the engine temperature on the instrument cluster. You won't see a physical thermometer; it's all electronic.