Originally Posted by Trekker
We haven't used the furnace so I don't think that the sound originated from it. We checked outside and it definitely was not a bird. The sound was ghostly...almost as though it was coming from an ipod or some type of digital system. The sound was quiet...not like the shrieking sound from a CO detector or smoke detector. I will check the house batteries to see whether there might be an alarm associated with them. However, we had been hooked up to electricity all night. It happened in the morning before we unhooked.
I bet it was coming from the hydralic levelers panel or under the dash. If the pressure is low or have a leak it will sound. If you are not level and on a steep incline it will also alarm. During this time you should get some type of blinking light on the levelers panel. To reset you may need to start engine and shut off to reset.