Whining noise from driver's side

Hi Ron,

How many miles on the odometer?
Any warning lights on?

I suppose you are aware of the normal inverter whine caused during regen braking; so if this is a new noise, maybe your transaxle is about to fail.

 

Hi Ron,

When you added new fluid, did you use 4 quarts of Toyota ATF WS?
Do you see any transaxle fluid leaks, especially at the drain and fill plugs?
Is the inverter/transaxle coolant reservoir at the full mark?

If you don't see any obvious problems, then I suppose you can continue to drive the car until something happens. The inverter is covered under the 100K mile hybrid system warranty but the transaxle is out of warranty, unless you have extended warranty coverage.

 

I solve the problem of whining noises from the driver's side by not allowing anyone else to drive my car

 

As an experiment, could you find a gentle downgrade, free from traffic, and try braking both in "N" and "D" and let us know if it makes a change to the noise?

If it has an electrical element, braking in "N" will mute the noise. If it is mechanical, it will happen with both "N" and "D".

Is the frequency proportional to the speed of the vehicle regardless of load (aka., up hill, level, or downgrade?) This helps us separate from the engine power path from the direct drive path.

Did you keep a sample of the transaxle oil from the last change? If the problem gets worse, I will be very interested in getting a sample for testing.

To eliminate wheel bearings and possibly tires, does it change with a left or right hand turn? Road surface effects?

One telling test would be if Toyota could run your car down the highway and read out the MG1 and MG2 temperature. If they are fairly close together, no problem.

Just a suggestion but perhaps you might upgrade your profile with location and vehicle age. ... Just to make it easier to follow your progress.

Bob Wilson

 

Good test Bob.

As a side note have you ever run out of gas & ran on electric until you found some gas in the life of this car?

Or has this car seen alot of high speed high way miles? Just trying to get a baseline of symptomatology as it appears you may have one of the rare CVT failures given all the symptoms especially low power poor mpg's.

If it is the CVT you will soon throw a Hi Volt DTC.

But the inverter may be overheating/failing.

Check real good for inverter coolant leak too. Coolant at correct level in the container next to the inverter? Ever had to add coolant there? Does it look and smell good and has it ever been changed?

You waited a long time to maintain the CVT. When you finally serviced the CVT was it because it started humming?

While engine is running is the inverter coolant circulating in the container? If coolant low look real closely around the sides and back of the inverter best you can for any red colored rust or coolant that may have leaked out of the inverter.

Good luck & Keep us posted please.

.

 

The coolant also passes through a channel in the transaxle to pull some heat. However, the Dept. of Energy studies indicate this is a minor effect. But if the inverter coolant change left behind an air bubble, there could be local heating.

Owch! The muted noise in "N" is not good because the inverter would not be involved. You called it whine, does the frequency vary with the speed?

Let's see how things develop and hopefully I am wrong.

We have seen a couple of NHW11 transaxle failure where a winding shorted. What happens is the permanent magnet in the motor becomes an unregulated generator and more and more heat is generated in the winding. Over time, this gets progressively worse and eventually fails the transaxle. The time varies but we've seen reports suggesting it can take 1-2 months.

If you can get your local Toyota service shop to do the following test, you'll get an early confirmation of the failure:

• run the car at highway speeds, ~55-60 mph, for 15 minutes -- to let the transaxle reach a stead-state temperature
• use the Toyota scanner to read out MG1 and MG2 temperatures

If the temperature difference is 30C or greater, the hot one is in trouble, serious trouble. Any temperature over 100C is pretty grim. This is only a HYPOTHESIS based upon the "N" test results. You really need the temperature reading to tell for sure.

To extend the life, try to keep the transaxle as cool as possible: (1) slow speeds, and (2) short trips. But this is a progressive problem. If you want to accelerate the failure, try a trip of a couple of hours at 75 mph.

Your repair options are expensive and d*mn expensive. We've seen one report of a salvage transaxle but it didn't turn out well. Rebuilding a transaxle is not trivial (aka., requires special tools and patience.) The Toyota transaxle replacement is likely to be pretty stiff. However, we know these transaxles are very robust and normally last a long time.

I am not trying to candy-coat or scare you, just share what the symptoms suggest.

Bob Wilson

 

Hmm..recent inverter pump replacement has me suspicious in a good way...You could very well have an inverter failure going on. Put the car in park. Make note of exact charge level/bar count in hybrid battery on mfd..how many blue bars..Open the hood and listen to the inverter. Is it screaming or otherwise complaining or really really hot. Coolant flowing in the red inverter coolant tank? Let the car sit there running with the air on full blast for about 30 minutes. Check the battery/bar count level. Is it charging up the hybrid battery pack ok?

BTW, the Scan gauge does not show MG temps. It only shows engine temp. The thing that checks MG temps is the Toyota toughbook diagnostic software gimmick Bob's talking about.

But given all the symptoms you will soon throw a DTC. Let us know what it is. The Scan gauge reads DTC's on the Prius and other OBDII cars also.

 

HelloI'm new to the "chat". I have a very similar whine from my 174,000 mile 2002.
I will try the D and N test and see what happens.
Just got new wheels and tires and was suspecting something there but it sounds electrical/regen to me.
Mine whine increases with a left turn.

Greg

 

Is this different than the light grinding noise I hear on my new 09? It kind os sounds like a tiny little air compressor charging up. It lasts about 3 seconds every few minutes.

 

Yes, that's different. What you are hearing is the brake pressure accumulator pump. The Prius can't use normal vacuum assisted power brakes, so it uses an electrical boost pump instead.

Tom

 

Thanks for the info.

 

What do you mean by "throw a DTC"? I think I missed something there.
Greg

 

He means a trouble code from the controller. Any major problem will cause one or more controllers to log an error code, which can be retrieved with a diagnostic tool.

Tom