Just bought a 2001 TT. Seller said battery was bad. I charged it and found it was good but was being drained over night. I hear a pump or small electric motor constantly running on the right side front of engine compartment. Could this be the auxiliary water pump? If so, Is the pump bad or is there some sort of thermostat that may need to be replaced? I am mechanically inclined and can do most work, just always had early muscle cars and this is the first Audi. Thanks in advance for any advice I can get.