HyCam noisy going down hill

Sort of. When the battery is full, the system will spin up the engine to throw away the excess energy of coasting on regen. Most of the time, it only happens automatically when going down hill. You activate it manually by selecting B on the transmission shifter.

 

could be the heat, and the battery not being able to accept the charge rate.
is there not an L on the shifter?

 

B is, or was, for brake on Toyota hybrids; it provides engine braking by spinning the engine to pump air. In some situations, like coasting downhill with a nearly full battery, the system engages it automatically. It might be labeled L on some models using the gear shifter assembly from an ICE version of the car.

Checking out the owner's manual, I see that Toyota did away with B and L for the 2018 Camry hybrid. Instead you got the S(equential) position; other makes call it manual mode. On the ICE models, this limits the max gear selection you want to car to use in order to provide heavier acceleration and engine braking. The hybrid doesn't have set gear ratios, but the control software mimics the same driving behavior as this gives in the ICE model.

From the manual, "A lower shift range will provide greater accelerating force and engine braking force than a higher shift range, and the engine revolutions will also increase." I can't say how the system is actually accomplishing the greater acceleration, but the engine braking is going to be done the way it has always been done in Toyota hybrids.

So the new Camry hybrid has the function of B gear in the S gear, but now gives you a range of engine braking amounts to choose from. Cars with the 4.2in display also get paddle shifters for controlling it.

The cruise control might have used engine braking to control speed. The manual isn't clear on how it decelerates the car. Or the battery was near full. Or the recent regen charge from coasting without engine braking heated up the battery enough that the system felt it best to take the load off it. We can't know exactly why without additional monitoring systems on the car. But the car switching on engine braking automatically while going down hill is normal behavior for Toyota hybrids.

Now I don't recall my 2005 Prius steering wheel ever shaking when engine braking was engaged. That might not be normal. Perhaps something is loose that started moving with the higher engine rpms.

 

Toyota calls it sequential, and it really is no different in operation than the 3, 2, 1 on automatic shifters back in the days for the ICE model. There is just 9 gears in the slush box now vs. the 4 or 3 back then. A person feeling frisky could treat it like a manual shifter, but its point for being there has nothing to do with sport, but with giving the driver control of engine braking on descents.

In the hybrid, it is just B, but with a choice of 5 steps to 'downshift' to instead of just the one in previous Toyota hybrids.

 

I'm checking out threads here on going down steep declines as I'm about to eat a big brake rebuild due to warped brake rotors (at 25,800 miles).

I've also heard the engine whining/racing noise as I've driven down steep declines here in Vermont (we have some steep roads up/over the Green Mountains). The noise is very disconcerting, but I gather, from everything I've read in the threads that it's nothing to be alarmed about. I'll just put car in B mode, pump brakes as needed, and disregard whiny noises from the system. Have I got that right?

Thanks!

 

Correct.

 

Could it be related to the road surface(s) or wheel alignment or a tire issue?

 

When using either regenerative or engine braking, the tire contact patches and the front drive axles are loaded; under stress. In theory you're feeling the same vibrations you'd get from them under hard acceleration. If it's more than that you might want to have it looked at.