Cruise Control Braking

[Diesel Benz]

I can't personally think of a scenario where CC would be decelerating a car hard enough to need the brakes.

The situation we're talking about here is where CC is using them to maintain a constant speed down a hill - i.e. to prevent the car from accelerating.

On the flat, altering the set speed while on CC is a reasonably slow process as it's done in small increments. Just reducing throttle would do the trick.

Yes, I did use a wrong word, I was thinking about a downhill case where the speed is maintained instead of being reduced. But like others mentioned, if the driver changes the CC setting significantly or activates cruise significantly above the set speed, brakes may be applied (I'm not sure about this case).

Anyway my point was just about the brake lights, if CC applies brakes, brake lights would also get lit.

 

[Shude]

Not entirely related but if going down a steep hill with the speed limiter engaged on my 202 if the speed creeps to about 10mph higher than the limit I set then the instrument cluster beeps at me! It only uses "engine braking" on the 202.

 

[haggis2768]

just bought w203,facelift model,could swear brakes were used whilst speedtronic is engaged.
not sure why handbook describes 2 systems,cruise control and speedtronic,

 

[evdok]

Not entirely related but if going down a steep hill with the speed limiter engaged on my 202 if the speed creeps to about 10mph higher than the limit I set then the instrument cluster beeps at me! It only uses "engine braking" on the 202.

Thats exactly how mine works (W211 E320)

 

[raymont]

Don’t use cruise much so not sure how that works wrt brakes. Do, however, use the speed limiter quite frequently. If you’re travelling at, say, 50 and select a limit of 30 then the car will be quite aggressive in attaining that speed. It will change down and brake. I know it’s braking as I have a slightly squeaky front brake and can hear it! Don’t know about the brake lights though.

 

[chrisbrad66]

My 2006 C class 320 cdi applies the footbrake for you when in cruise control, it first happened when i towed my caravan in derbyshire, the cruise was set at 50 and i was going down a steep hill with my foot covering and just resting on the brake pedal, when the brake pedal actually moved downwards away from my foo!! it scared the s--t out of me!!! so i found another steep hill to prove to myself i wasn't dreaming and the car actually applies the brakes for you to maintain the set speed if it can't do it by engine braking alone, very strange to get used to but very usefull when you do.

 

[timskemp]

Thread resurrections R us...

My W204 definitely brakes when slowing back to cruise speed, but the brake lights don't come on... is that by design???

 

[kwakdonut]

I believe the 'later' MB's did this and is perfectly normal. My previous car, a 52reg E320 just slowed down naturally.

 

[Benzster]

There have been discussions before about whether braking operates to reduce speed with CC on.

I've certainly been under the impression on on long downhill runs that on the W211 the SBC brakes are used to regulate speed if engine braking is insufficient.

Today I found myself at the top of a steep incline I'd reckon was 1 in 8 on which I previously have had to use the brakes all the way down to hold within the speed limit. With the the foot off the accelerator and the car accelerating through 30. As an experiment I flicked the CC lever to set 30 and immediately the car decelerated very strongly and then held speed all the way down. The SBC pump also activated on the way down.

So I'm convinced that where CC and SBC are fitted that the CC has authority to use the brakes and use them quite forcefully as well.

I'm sure the brakes are operated when going down steep hills with CC on, in my W219

 

[Dryce]

I'm sure the brakes are operated when going down steep hills with CC on, in my W219

W219 also uses SBC.

 

[jefrs]

S210
The Anti-lock Brake System (ABS), does what it says.
The ESP (Electronic Stability Program) applies brakes without putting the brake lights on. ESP Supplements ABS and ASR (Acceleration Skid Control), if you have ESP you have ASR.
ADS is Adaptive Damping System, has nothing to do with brakes but works with ESP.
The Brake Assist System (BAS) is a powerful panic brake system, if you hit the brake suddenly and hard, the car stands on its nose. It works. Which is nice to know but nothing to do with Cruise/Speedtronic
The Cruise control can set cruise and minimum speeds, you can accelerate above the cruise setting and fall back to it.
The Speedtronic system is a speed limiter, you still have to use the throttle.

S210 Experiments 1 & 2
Near here is a long straight hill of about a mile, in a 30 limit. Handy. So I set (1) the Cruise then (2) the Speedtronic to 30mph and take my feet off. The car descends the hill, the throttle shuts, then it down-shifts, then it flashes the dash console warning "LIM" triangle with "over-speed", then it applies the brakes. I have no idea whether it puts the brake light on when it does this but on a steeper hill it cannot hold the speed down so I presume it is only set for gentle braking.

 

[nrg220]

Cruise and braking

My W204 2007 C Class does definitely brake with cruise on, when downhill, when reducing the speed on the motoway by 5mph clicks.

I was surprised when I first used it that the car brakes itself to get to the speed set, always wondered though if my brake lights come on as well? Still dont know and Ive had the car a year now

 

[timskemp]

My brake lights do come on when cruise applies the brakes, contrary to my previous post (confirmed by friend following in another car)

 

[SchwarzesAMG]

Same thing in my W209 MY2005

 

[kidkatarakte]

My previous 2007 w203 did brake on CC and it lacked SBC unit. But, my 2004 w211 now I am driving does not brake on CC. SBC module does not work properly and should be replaced. I wonder, whether CC will apply brake when SBC module is replaced.

 

[timskemp]

My previous 2007 w203 did brake on CC and it lacked SBC unit. But, my 2004 w211 now I am driving does not brake on CC. SBC module does not work properly and should be replaced. I wonder, whether CC will apply brake when SBC module is replaced.

Nope. My 2003 W211 with SBC did not brake on Cruise or Limiter,

 

[corned]

Coming back from Whitby last Saturday in the dark, I was on cruise coming down one of the roads off the moors. The car held the speed down the hill, and took it upon itself to at least put on the brake lights. With mine being an estate, I could see the high level lamp illuminate the tailgate window aperture, with my feet nowhere near the brake pedal.

 

[greekCL]

Try to accelerate fast ... and then on a small incline lift from the accelarator rapid ... you will see how fast the seat belt locks ... I though someone hit me from somewhere... frightening experience!!

Ths is the BAS coming to action without even pressing the brake pedal.

Now the braking of the CC I have experienced it ... however it does not always happen... strange.

That is on my W215 '00 without a distronic.