I have now had my TCH for 11 months and about 22,000 miles and have grown accustomed to the 38-40 mpg steady mileage (I seem to get best mileage at 55-60 mph on cruise control, which is most of my commute) and have not needed anything other than the 5000 mile oil changes. I also like the mild soft whine of the electric at low speeds, knowing it's saving me plenty over the course of this past year.


About a month and a half ago a new whine developed which became noticeable at higher speeds, especially over 45-50 mph. It would increase and decrease with pushing down and letting off the accelerator, and would disappear with shifting into neutral, as going down a hill at 55 mph. I was concerned parts would need replacing, but it was otherwise driving well and I decided to leave it until my next service, and have put up with its annoyance since then when at higher speeds.


A week ago while driving in cruise control I happened to press my toe on the soft bulge in the carpet behind the accelerator and noticed the whine increased. If I stopped it went back to its usual pitch, but when I pressed the bulge in the carpet again (several times to be certain) each time it would promptly increase pitch, and then just as quickly return to the usual whine I had been noting when I took my foot off. During this the car was keeping its steady speed with the cruise control.


Yesterday, again while driving in cruise control and listening to this new whine I had been unhappy with for the last month, I randomly pulled the tip of the carpet down with my toe, and the whine suddenly, surprisingly, and completely disappeared. It has not come back, I have kept my foot away from that area of the carpet, and the usual quiet drive I had been so used to has returned.


I haven't looked to see what in the engine compartment just behind the accelerator causes this (perhaps others on the forum could help with that), but I thought would be worthwhile to mention, since surely others may run across this simple cause of a whine that actually may be fixed without major service. Toyota may also want to consider a simple design change, to prevent unrecognized pressure from a foot creating this. Since this is difficult to repeat while the car is stopped (pressing on the accelerator won't “rev” the electric motor), and only is loud at higher speeds, the service department may not be able to replicate it in the shop, and other parts may perhaps be replaced in trying to fix this complaint. Bottom line advice: Avoid pressing your foot on the carpet bulge behind the accelerator while enjoying the quiet drive in cruise control.

 

I dunno, but I think I'd want to know why it was doing that. Too bad you fixed it - now you'll never know...

 

SummerTCH — I can't make any sense of this at all! From your second paragraph, it sounds like a motor-generator whine (since it disappears when you shift into 'N'). But, in your third paragraph, you say that the whine increased when you pushed the carpet, while travelling at constant speed in cruise control. This seems to rule out motor-generator whine. I have no "bulge" in the carpeting under the accelerator of my TCH, and indeed I don't believe that anything is supposed to be under the carpet there. Pressing there makes no difference in my TCH. Why don't you pull your carpeting down and see what you can find? Do let us know!

Stan

 

I will have to admit I don't have an explanation yet, but hope I might get some ideas from the service crew when I take it in for the 25,000 mile oil change later this month. The ridge in the carpet is just to the left of the staples just below and left of the black cylinder between the accelerator and brake pedals. I took a picture to try to help show this spot better. I have had absolutely no problem since my last post; the car is quiet and smooth as can be, and driving great.

 

It sounds like a piece of soundproofing (or a soundproofing plug) under the carpet started coming loose and you ended up pushing it back into place with your toe. A lot of soundproofing was installed to block the whine of the motor/generators which would be quieter loud if the soundproofing was not in place. You probably just heard the normal whine from the motor/generators, but without sound proofing.

 

Great! That sounds like it very well is the explanation - certainly would fit well with how things went. Such a simple cause (and solution) if it should reappear later. Thanks!