Looking for some help from the 200 or so of us who own one of these rare birds.

I'm not new to GS Hybrids... My first was a 2008 so I am accustomed to the usual (unusual) noises that these cars make as the hybrid system engages, charges, does regenerative braking, etc.
But my 2016 has added a few new noises... At very slow speeds (<1 mph) the car makes a high pitched ringing noise (almost like some one playing glasses... think Sandra Bullock in Miss Congeniality). It does this if you are coasting with out any brakes (so its not a rubbing rotor) and it does it in Drive, Neutral and Reverse... so I don't think it is tranny related.
It does this for three or four rings (ring ring ring ring) as you stop and as you start. Very faint almost imperceivable but once you hear it, you hear it every time. No biggie in regular driving, but in stop and go traffic jams it can get annoying (edit it IS annoying). Seems to be coming from under the hood on the passenger side.. maybe up at the cowl.

But wait, there is more. If you start in a "spirited" way and you jump on the gas from a stop. Then you get a single faint BEEP along with the ring ring ring sound. The beep is the same pitch and tone as the beep you get from the parking warning system... but again very faint.

Anyone else hear this?
Anyone have any idea what the heck it is?
And most important... Anyone have any idea how to turn it off.

 

The inverter is located in the engine bay where the battery is on the nonhybrid models (i.e. passenger side, right next to the cowl). Just a thought.

Does the high pitched ringing noise only occur while moving? The car has two pumps that run basically at all times - the water pump for the inverter coolant circuit, and the auxiliary transmission oil pump (runs when in EV mode to maintain pressure on the MG2 clutch packs and in other conditions to... provide additional pressure, I guess).

At any rate - none of the things that I just described are much different to your older (and mine current) model - the inverter is in the same location but completely redesigned (and absolutely bulletproof, from what I've read, don't worry about it ), the transmission is basically the same, the water pump... should be extremely similar?

One more thing - since you're in the US (like almost everybody here), the 3rd gen 450h in the US(&Ca - basically federal standards spec) & Japan specs have a 3.769 final drive diff, while the EU/General(literally everything else - Singapore, Australia, you name it) have a 3.266 diff. With the 4th gen they settled on a 3.266 for both - hurting off-the-line acceleration and improving top speed (which is limited by MG2's max RPM). Point is - I swapped in a US diff (out of an US-spec SC430 - literally same asembly, part number-wise) and the car did start making "different" noises at different speeds - the EV motor noises have a different pitch and higher intensity, at least at <~20mph (30kph here) residential area speeds. I don't think that it's what you're describing, but it's worth noting anyways - the inverter whine (high pitched power supply type whine) is a bit more perceptible with the tall diff than the short diff, vice-versa for motor whine.

No clue about the beep - might be linked to the EV mode being on and the car starting the engine due to power demand or something like that?

 

Own a ‘16H with 50k on it. I’ve heard none of these issues or noises you describe.

 

Lwerewolf,

I assume your off the line performance and torque (felt) dramatically improved with your differential swap. How much of hit did you take off the top end? Did you correct your speedo, and ECU related items?

 

Speedo/etc is controlled by ABS sensors - no changes.

Low-end performance is drastically improved. Fuel consumption is practically the same, as far as I can tell so far. Top end - the 450h pulls until MG2 hits the rev limiter. Max power comes earlier due to the way the CVT works (the engine can get to max RPM earlier without overrevving MG1 - curious note, the 2012+ 450h hits max power at 6k rpm, which is quite beneficial in this respect). If you for some reason care about vmax - not the mod for you

I think I've read of at least one other person here swapping their 4th gen gs450h diff to an aristo vertex 3.769 torsen unit - requires swapping and modifying aristo axles (to remove the ABS rings - since ours are in the hub). Probably the best person to ask since mine is a 3rd gen. Other than that - let's not derail this thread further

 

Thanks for the response! While moving? yes but just barely and only for a second, maybe two. The sound is short lived. It only occurs at very low speeds (walking pace). And only for a second or two while coming to a stop and while starting up again. Once you are moving (say 5 mph) the sound is gone. It seems to only happen during "electric" mode. During warm up (with the gas engine always running) or once the gas engine kicks in it is not present. Also if you feather the gas or run the car in electric mode.. it makes the noise for a second or so and then stops. The beep only occurs if you "give it the beans" and the gas motor kicks in from the start... then you get a faint short beep.. (one beep) . The ringing is hard to hear, the Beep is also very subtle.

Is there any chance this is some sort of pedestrian warning system? Do our cars have one? If so anyone know where the speaker is on a GS?

 

Update.

So my wife and I are still enjoying this super rare car. This summer during a road trip to the Alberta and Montana badlands and across the prairies it was getting almost 40mpg. Amazing car.
As we were going through the Rockies I got a really bad rock chip in the windscreen. After a fair bit of work with my insurer I found a local Toyota dealership that could process my glass claim (and not mess up the HUD, Lane Departure, De-icer, Pre-colision, Rain Sense, Auto highbeam etc)

Car is back with new Lexus OEM glass, perfect job and low and behold the annoying ringing sound is gone.

Pretty sure the noise is from the ABS system, and must have been coming in via a gap in the bottom of the windshield glue? According to CarFax this car has had its windshield replaced at least once before

 

Wife is looking for a new car and this is one that keep popping up. Any new updates to share? how many miles on it now?