Where's the "control" in Cruise Control?

toyota
hybrid-repair
camry

#1

I’d like to know how cruise control is supposed to work. I have a 2009 Toyota Camry Hybrid and on a trip to Yellowstone last year, I used the cruise control quite a bit. However, what I noticed was that even though I would set the cruise control, whenever I went down hill, the car would accelerate up to 20 mph over the speed I had set the cruise control. Driving from Oregon through Idaho and in to Montana, you have areas where the posted speed is 75 mph, and when we would go down a hill the car would get up to 90 + miles mph. I brought my car in for the Toyota recall issue and asked them to fix this, but they tell me the cruise control is supposed to accelerate. I’m having a hard time trusting that is true b/c any other car I’ve ever had would regulate the speed. So if I was going up a hill, it would accelerate to keep it at the set speed. And when the car was going down hill, it would let off the throttle so that the car would slow down v. requiring me to push on the brake to slow the vehicle. Can you please help and tell me, where’e the control in cruise control if the car doesn’t reduce its speed when going down hill? Seems dangerous to me.



Thanks!

Sheila


#2

Your cruise control system will accelerate but will not operate the brakes. Should you exceed the set speed your vehicle will cruise without effect from the cruise control system. If you’re descending an incline steep enough for gravity to overcome resistance, your speed will increase even if you’re above the cruise control setting.

In short, the system was operating normally.


#3

I can only reply from a recent rental car, a Chrysler 300. The car would automatically downshift to control speed in the big hills of HWY 101 in CA, I would think the specs you have provided are out of normal.


#4

The cruise control is acting normally. The cruise control is not accelerating as much as it’s gaining velocity going down the hill. Most people step on the brake when the vehicle starts gaining speed down a hill. This disengages the cruise control and the driver takes over control of the speed using the brakes. There is no cruise control in existence that operates the brakes. I for one am very grateful for that.


#5

If the hill is steep enough to require braking, cruise will NOT provide that. It’s not an autopilot…It will close the throttle, but on a steep grade, it’s up to YOU to DRIVE THE CAR!!


#6

Cruise control cannot defy the laws of physics. When you’re going down hill the momentum will cause your car to speed up. The best the cruise control can do is to close the throttle. Virtually every car made in the last 40 years with cruise control does this. There are some high end cars with radar assisted cruise control that will automatically apply the brakes should you come up on a another car directly in front of you, but you mainly see that in Lexus or Mercedes Benz models.


#7

Can you duplicate this near your house? If so, I would get a demo from the dealer and see if a different Camry Hybrid acts the same way.


#8

I remember hearing a nutty story once of a person who truly did not get this. I probably have it a little wrong and it may be an urban legend, but it was about someone who truly didn’t understand that they still had to drive the vehicle. It was something about some character who rented or bought an RV. They’d never had cruise control before and took it as a smart luxury item. Got it on the highway set the cruise control and then got up to go to the back to make a pot of coffee - disaster ensued.

The only thing that surprises me about the Camry is that engine didn’t provide enough braking all on its own to keep the speed down. But I don’t know how its hybrid system works, so I’d guess it has something to do with that.


#9

Lexus IS model cruise control down shifts to maintain speed going down hill…If your’s has regenerative braking, I would say it’s a poor design with other options at it’s disposal other than your foot and a really expensive car. It is normal, but if I paid that much for the car, I’d expect something better.


#10

"There is no cruise control in existence that operates the brakes. I for one am very grateful for that."
That’s not true. The more expensive cars have this. They will even brake to match the speed of the car in front of you.


#11

A hybrid is “free-wheeling”. The engine is not connected directly to the wheels. In effect, the car was coasting down the hill out of gear. There ARE no gears…The electric motor becomes a dynamic brake, but someone has to step on the brake…Cruise Control, except on high-end luxury cars, does not brake for you…


#12

#13

That makes sense - thanx


#14

Those vehicles have “adaptive” cruise control systems that brake to match the speed or to avoid the vehicle in front. They do not operate until a vehicle is in front so topping a hill with no traffic will just allow the vehicle to gain speed. The driver needs to “drive” the vehicle at all times when using cruise control. We are getting into apples and oranges here.


#15

I recently rented a 2007 Honda Civic Hybrid and its engine and transmission provided very little resistance once you release the throttle. But as soon as you’re going downhill with cruise control active, regenerative braking kicks in. I’m surprise that Toyota doesn’t do likewise. The Federal Motor Vehicle Safety Standards require a transmission position that provides extra resistance. In the Camry Hybrid, I think that’s the “B” position.


#16

2006 ford Escape hybrid is the most dead-on accurate cruise I’ve ever owned.
Set for 75mph.
Up nine mile hill, Albuquerque, 75 mph.
down nine mile hill…75 mph

Even my old cable operated cruises would only gain 5 mph max down hill, but would lose 10 or more uphill. The Escape barely wavers.
Does the Camry have an “engine braking” or LOW selection in the gear shift ?

When you DON’T have the cruise on and you’re descending a hill, can you simply let up on the gas and control the speed ? If so, there’s something wrong with your cruise.

I’ve never known a cruise to gain that much.


#17

"2006 ford Escape hybrid is the most dead-on accurate cruise I’ve ever owned.
Set for 75mph.
Up nine mile hill, Albuquerque, 75 mph.
down nine mile hill…75 mph "

Though it may incorporate other means, poor aerodynamics of the Escape must help a lot too. :slight_smile: