Cruise Control Braking

[Dryce]

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.

 

[alexander patie]

that is interesting to know, and i confess, a new one on me.

 

[whitenemesis]

Is it not mentioned in your handbook?

 

[lynall]

My w210 will downshift the box to pull the speed down with the limiter set.



Lynall

 

[corned]

Interesting, Dryce.

Would the brake lights come on in this situation? If so, that would be the give-away.

 

[sym]

On the W203, my brake pedal actually physically moves when the CC applies the brakes ! So I would expect that the brake lights come on ! Quite a weird feeling when your foot is hovering over the brake !

I'm sure this is a documented feature in the handbook, but have not checked.

S.

 

[renault12ts]

Mine will hold a constant speed up hill and down dale. But I would be interested to know if the brake lights are activated. I don't think they are because your brake light would be constantly on and off if you are traversing hilly country.

 

[corned]

In the old days - real Minis for example - had a pressure switch in the brake line to activate the lights, so any brake fluid pressure would trip the switch.

More recently, it has been more common for a switch to be fitted to the brake pedal arm, so pedal movement is required to activate the lights. It would be interesting to know which way the 211 goes. If SBC is capable of actually applying the brakes for other than cosmetic reasons (the disc-drying routine in wet weather for example - if it still does this?) then surely the lights must have to be activated for the traffic behind?

Or maybe it can do it both ways??

 

[Dryce]

Would the brake lights come on in this situation? If so, that would be the give-away.

I believe not.

• AIUI the brake lights are a signal activated from the brake pedal.
• The brakes are being used to maintain speed and not reduce.
• Bit difficult to see your own brake lights.

However with regard to that first point I believe the brake lights are on when SBC-H is activated when stationary. But in that situation the brake lights would already be on prior to the hold being engaged.

 

[whitenemesis]

On the W203, my brake pedal actually physically moves when the CC applies the brakes ! So I would expect that the brake lights come on ! Quite a weird feeling when your foot is hovering over the brake !

I'm sure this is a documented feature in the handbook, but have not checked.

S.

I didn't think 203 had this feature as it is only available on cars with SBC, not an option on 203.

 

[BTB 500]

The CC on our Vito uses the brakes. From the handbook

Cruise control
Cruise control maintains the speed of the vehicle for you.

On long and steep downhill gradients, especially if the vehicle is laden or towing a trailer, make sure you shift to a lower gear, or to shift range 1, 2 or 3 on vehicles with automatic transmission, in good time. This utilises the braking effect of the engine. This protects the brake system and prevents the brakes from overheating and wearing too quickly.

Pretty sure that on older Mercs like my SL it only operates on the throttle though. Possibly came in with Speedtronic (which the SL doesn't have)?

 

[whitenemesis]

203 has Speedtronic but doesn't apply brakes on downhill.

Checked handbook and states CC may not be able to maintain selected speed on steep downhill.

 

[BTB 500]

Maybe part of Brake Assist then (which the Vito has)?

 

[pmtx]

Not sure if this helps the debate but my 211 still has SBC Stop and that definitely illuminates the brake light when stopping in traffic.

 

[corned]

The CC on our Vito uses the brakes. From the handbook

This utilises the braking effect of the engine. This protects the brake system and prevents the brakes from overheating and wearing too quickly.

Hang on Bill - that proves it doesn't use the brakes!!

 

[whitenemesis]

Maybe part of Brake Assist then (which the Vito has)?

203 has Brake Assist also....

 

[SilverSaloon]

no they dont. unless you have radar cruise.

 

[whitenemesis]

no they dont. unless you have radar cruise.

Is Brake Assist the same as BAS?

I've just read further and yes it is

Page 68/69 in my handbook

 

[sym]

I didn't think 203 had this feature as it is only available on cars with SBC, not an option on 203.

I can assure you that mine does! Its a MY2006 - perhaps its only on the later ones ?

It will only apply brakes if you hold down the de-accel lever for more than a couple of seconds when cruising at 70mph-ish ... otherwise it just cuts the throttle slightly if a small decrease in speed is required.

S

 

[timskemp]

I don't think mine has never done so, in fact it will bleep if the speed goes over the set cruise and cannot be maintained. The 2007 facelift non SBC rental E280CDI I had would though, and illuminated its brakelights when doing so.