The noise I hear does not change in pitch which would be inconsistent with a motor noise. Also it comes from the right rear of the vehicle. I've heard a lot of motor noise and a lot of electronic noise in my career and this sounds like electronic to me. Kinda like the noise made by the sweep generator circuitry in a tv, back when that sort of thing happened.

JG

 

I think it is the battery cooling system you hear, myself.
Not normal, but from the cooling system.

 

Is it a high pitched "eeeeeee" noise, relatively unchanging as you motor along (accel or decel) in electric-only mode with the windows down? Have you tried shifting to neutral and seeing if it stops? Do this in a safe and open area where it's quiet and there's some echo, like a parking garage.

 

If the noise is an electronic-type "whistle" whose pitch doesn't change with motor speed or accelerator position, it sounds to me as if it likely is the oscillator in one of the dc-to-dc converters. There is one near the NiMH battery, and maybe also one near the 12-V battery, isn't there?

Stan

 

Hmmmm....If its a switching power supply thats a possibilty (and its likely that it is a switcher) The noise itself usually comes from the inductors. I had a fab mismount a component in a switching power supply I designed and the inductors in it started to oscillate audibly. Little tiny inductors smaller than your fingernail made an amazing racket for there size and the inductors in the FEH would likely be much larger.

 

TeeSter — Yes, these are indeed switching dc/dc voltage converters and dc/ac and ac/dc inverters. The noise can come from both the inductors and the switching power transistors, in my experience. In the TCH the switching frequency lies between 1.25 kHz and 10 or 15 kHz if I remember correctly. Since jginaz said that the frequency did not change as a function of motor speed or power, I concluded that it likely would be the dc/dc converter, which probably runs at a fixed frequency. (The Toyota motor/generator inverters change their switching frequency as the motors' speed changes.)

Stan

 

Excellent suggestion. It is unchanging in accel or decel yada yada. I will do the put in neutral test n see what's up. My guess is, it will go away as again in accel or decel it makes the same noise, i.e., when there is load (positive or negative) on it is when the noise happens--in EV only, once again.

 

Yes it is, but I would say it does have the quality of metal dragging on metal, where at least one surface is not totally smooth. High pitched grinding noise might be apropos.

 

My first post to the forum, but I've been lurking a bit. Months ago I found this forum because I was looking for a cause for the *exact same* noise that is being described, except that in my car, it would happen in electric mode and also at higher speeds in gas mode. It had the distinct sound of metal on metal -- it was also the right rear wheel. My husband could hear it from across the parking lot. It first showed up after a hard rain, but I don't know if that's related.

Dealership found nothing, because of course it was silent the day I brought it in, but the next day the noise was there again, only for awhle. Later I picked up a nail in that tire and after they pulled the tire and fixed it, the noise never returned.

 

Great story Lisa. It may be something this simple. And also, I discovered it IS NOT in EV only mode--just easier to hear in EV only mode.

Noel