We had a few cold nights lately and my Prius is parked in my garage. When the car is off several hours, I keep hearing a noise coming from the back passenger tire area and a clicking relay every once in awhile from the front of the car's relay box. It sounds is like a humming or fan sound. I'm not really sure what the sound is and the car is turned off for several hours. I thought maybe it was some sort of heater for the traction battery or something. Anyhow, this relay clicks this noise on and off throughout the night until I use the car again. Does anybody know what it might be and is this normal? The car runs great as always, battery level looks great everytime I use the car. Thanks.
From page 22 of the Owner's Manual: Approximately five hours after the hybrid system is turned off, you may hear sound coming from under the vehicle for several minutes. This is the soundof a fuel evaporation leakage check and, it does not indicate a malfunction. There has been another thread on this subject and it is normal.
Thanks for the information. I heard it again tonight(the car has been off for at least 5 hours) and having the car for over a year and just now hearing it for the first time suprised me. Thanks.
Try this: Remove hatch floor and rear cargo tray. Turn on the car. You'll be surprised at all the strange noises you'll hear.
