Since the weather warmed we have been driving with the windows down and notice when our 07 FEH is in EV only mode, particularly in alleys or areas when sound reflects back to the vehicle from the sides, a steady screech, for lack of a better word, eminates consistently the rear of the vehicle (as near as we can tell). As soon as ICE kicks in, you no longer hear it. It is noticible when the vehicle is both accelerating (yes, very slowly!) or decellerating as in the regen braking routine.

Is this most likely standard equipment, or is it a defect that can be repaired? We have not yet contacted a dealer about the noise.

The other reported sound issue, the intermittent "chirp", seems to have been with us only rarely, and hardly at all lately in the warmer weather, so we haven't taken action on it either. Our FEH now has 2500 miles on it, and averages just over 27 mpg, which I feel is reasonable since much of our commute is in the 1.5 miles range, so not optimal for the most efficient use of gas and the hybrid technology per se.

Anyway your thoughts on my rendition of the screech described would be much appreciated.

Noel

 

I've heard it too and my theory is that it is magnetostriction noise from the DC-DC converter transformers. I have no proof.

JG

 

Is it really a screech, or more like a buzz, hum, or whir?

There are 2 electric water pumps, one electric brake fluid pump, as well as the DC/DC converter and other electronics related to the transmission.

My suggestion would be to run it next to, and compare it to another vehicle of the same year and see if the sounds match.

Oh... don't forget the variable speed cooling fan in the back for the HV battery. There is also an air vent door in the back that opens and closes. If the door was not adjusted or installed properly, or "squeaky" like an old wood door, that could explain the chip. My 2 cents.

-John

 

John I don't think it's a buzz, hum, or whir. It kinda sounds like your brakes might sound if they were wearing directly on your rotors. It's steady though not 100% non-variable in pitch, a sound like metal-on-metal, and I think screech isn't too far off. I kinda doubt it would be a cooling fan, as it really sounds like no other fan I've heard before. Perhaps it could be something in the rear brakes. I hope so cuz that would be easy to fix probably.

 

Your description is vaguely familiar to some reported noises that I believe were solved by adjustment of the parking brake (drum style inside the rear brake rotors)....perhaps a search on parking brake issues/noises(?). I think diagnosis was performed by quickly moving the brake lever up and down (while continuing to hold in the button)....while the noise is occurring. Be safe.

 

It's a thought, but I luckily have disk brakes x4. I will try moving the parking brake as you suggest though :o). The fact that it always happens accel or decel in EV only seems to suggest it wouldn't be related to brakes. Who knows tho I appreciate the tip and will try playing with parking brake while the noise is happening. Thx!

 

I think you're hearing electric motors. My Prius made the whine, and I was surprised to notice my FEH makes the same noise. It's nearly identical. It's more noticeable at low speed with the windows down in a quiet area like an alley, or driving passing a building or wall that reflects sound back to you.

I heard the noise the other day while I was out my front garden. It sounded exactly like my FEH. looked up and it was a neighbor cruising past my house in his Highlander Hybrid. They all pretty much sound the same when they are in electric-only mode.

 

I will have to double-check the shop manual but, I thought the parking brake was drum-style inside the rotor for your rear disc brakes.



mtberman could be on to something....

many of the normal motor noises are high-pitched.

 

Hmm, never thought about that. Makes sense though that the parking brake wouldn't have a non-hydrolic connection to disk brake calipers.

 

This is kinda my guess two since the motor in generation mode or drive mode is still one device, which is compatible with hearing the noise on accel or decel.