New Guy...Question About Adaptive Cruise Control

[bbinwv]

Hey all. New guy here, just bought 2011 LTD and this sight was a great resource for real owner info while I was making my purchase decision between the EX and a couple other candidates.

Hopefully I'm in the right place for this question. Go easy on me if not.

The sales manager at the dealership explained that the Adaptive Cruise Control used the transmission to control the speed of the vehicle when you approached a slower vehicle or whatever.

As I read the owner's manual, it appears that is incorrect (imagine that, a dealer not knowing what they were talking about). Actually, the ACC uses the brakes to control the speed. The manual has several references to the the brakes including stating that the ACC will be disabled if the brake temperature gets high.

So.....does that mean that when I'm cruising at 70 and come up behind a car doing 50, the ACC uses the brakes to hold the Explorer speed to 50 MPH? It seems to me if that were the case that would cause:

Excessive wear to the brake pads/rotors and
Excessive strain on the engine and
Impact the gas mileage severely.

I can't believe that this is the way the system works. Am I missing something? Can anyone shed any light on this for me? Sorry for the long post but this really bothers me.

 

[baxterdown]

Hey, welcome to the forum. ACC will apply the brakes when needed. I have had mine set at 80mph and traffic has slowed down ahead to 30mph. The system will coast when it can, but will apply the brakes when it requires to slow the car such as in the case above.

I know what you're gonna ask next.... how slow will it go? The answer is 15mph. ACC disengages when the vehicle slows down below 15mph. Above that, have fun freaking out about not having control of your car's speed! I do it all the time!!!

 

[Jimmy-B]

It is pretty disconcerting, but it's also pretty cool. The gap adjustment is very clever, as is the way it accelerates back up to speed if a gap opens up or if you pull out into a clear lane.

You can always switch the adaptive part off, too, and just have 'old fashioned' cruise control.

 

[sdm9465]

So.....does that mean that when I'm cruising at 70 and come up behind a car doing 50, the ACC uses the brakes to hold the Explorer speed to 50 MPH?

In case it wasn't clear from the other replies, yes, the ACC will use the brakes to slow you down. It does not use the brakes to hold the speed down though. Basically the ACC set point is no longer used when you are following behind a vehicle travelling at a slower speed. Instead the ACC controls the throttle to maintain the gap you have set. Brakes won't be used again once you have slowed down unless you are going down hill or the vehicle in front of you slows down more.

 

[FordService]

...I can't believe that this is the way the system works. Am I missing something? Can anyone shed any light on this for me?...

Welcome to the forum, bbinwv! I was advised that the Adaptive Cruise Control uses engine braking. The transmission does not downshift, but it also does not coast or disconnect from the transmission. So the friction from the engine is slowing the car. I hope that answers your question!

Cory

 

[harlenm]

So.....does that mean that when I'm cruising at 70 and come up behind a car doing 50, the ACC uses the brakes to hold the Explorer speed to 50 MPH?

It works just like any other cruise control system, it just has the ability to adjust the speed based on vehicles in front of you. Once it determines the speed of the vehicle in front of it, it changes it's speed settings.

As soon as it senses no obstacles, it goes back to it's original setting.

 

[drober30]

In case it wasn't clear from the other replies, yes, the ACC will use the brakes to slow you down. It does not use the brakes to hold the speed down though. Basically the ACC set point is no longer used when you are following behind a vehicle travelling at a slower speed. Instead the ACC controls the throttle to maintain the gap you have set. Brakes won't be used again once you have slowed down unless you are going down hill or the vehicle in front of you slows down more.

This makes sense! I was wondering f the system was "riding the brake" to keep the vehicle at the slower speed. That would not have been good.

 

[Car 54]

The only thing I don't like about ACC is that when you drive another car without it, you have to scare the crap out of yourself before you realize it's not going to brake for you.

 

[sangiovese]

The only thing I don't like about ACC is that when you drive another car without it, you have to scare the crap out of yourself before you realize it's not going to brake for you.

This is my biggest concern about ACC, BLIS, curve control and the other safety gizmos. They're great but you can get used to them. And you have to remember they're not there when you drive your other car.