Distronic and brake lights
Thread Starter
Junior Member
Joined: Jan 2012
Posts: 50
Likes: 3
2012 e350 wagon
Distronic and brake lights
Anybody know how the system handles this?
Great long drive in our e350 wagon the last few days, and used the Distronic much more than before -- from set at 73 all the way down to 20 or so, and back up. System works very well.
But...does it turn on the brake lights when it slows? Or only when it slows a certain amount? Anyone have any idea? I know that the hold feature leaves them on. Seems it would be safer turning them on, but only when it uses the brakes rather than easing up on the throttle.
Great long drive in our e350 wagon the last few days, and used the Distronic much more than before -- from set at 73 all the way down to 20 or so, and back up. System works very well.
But...does it turn on the brake lights when it slows? Or only when it slows a certain amount? Anyone have any idea? I know that the hold feature leaves them on. Seems it would be safer turning them on, but only when it uses the brakes rather than easing up on the throttle.
Super Member
Joined: Jun 2011
Posts: 576
Likes: 8
From: Placitas, NM
E550
Good question. I've had cars with the lights driven from the master cylinder, others driven from a brake pedal switch.
In my experience, it doesn't touch the brakes except in an emergency. Otherwise, "slowing" seems to be accomplished by reduced throttle and down-shifts.
In a computer-perceived emergency, with Distronic Plus with Brake, I will only assume the brake lights come on -- don't know how to test safely.
In my experience, it doesn't touch the brakes except in an emergency. Otherwise, "slowing" seems to be accomplished by reduced throttle and down-shifts.
In a computer-perceived emergency, with Distronic Plus with Brake, I will only assume the brake lights come on -- don't know how to test safely.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Good question. I've had cars with the lights driven from the master cylinder, others driven from a brake pedal switch.
In my experience, it doesn't touch the brakes except in an emergency. Otherwise, "slowing" seems to be accomplished by reduced throttle and down-shifts.
In a computer-perceived emergency, with Distronic Plus with Brake, I will only assume the brake lights come on -- don't know how to test safely.
In my experience, it doesn't touch the brakes except in an emergency. Otherwise, "slowing" seems to be accomplished by reduced throttle and down-shifts.
In a computer-perceived emergency, with Distronic Plus with Brake, I will only assume the brake lights come on -- don't know how to test safely.
The way I think it works is the cruise control does use brakes when ever it needs to do so to keep car speed at setpoint going down hill or to slow behind another car with Distronic but the brake light does not come on most of the time.
I think the thinking here is that if the slowing down is at rate a manual geared car would do with only engine slowing it down the brake lights are not used. If slowing down is more aggressive then the lights come on.
To test for this is quite safe and simple to do. Go drive on a highway say 55 mph on empty road and hit the CC stalk down once or twice and see how car slows down clearly using brakes. If you hit the stalk three times very quickly, i.e. ask for 15 mph speed reduction (make sure you are at even fives before hitting the stalk) the car slows down much quicker and this time also the brake lights come on. This is how my 2011 E350 worked (without Distronic) and this is how my current ride 2010 E550 with Distronid does it.
If you test at dark you will clearly see the brake light when it comes on.
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Joined: Sep 2006
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From: Clear Lake Shores, Texas
2026 AMG CLE 53, 2026 BMW X5, 1972 Corvette
The brake lights definitely light up on my 2012 with Distronic when it slows the car down. I'm not sure it does under gradual deceleration but it does when the system applies the brakes.
Super Member
Joined: Jun 2011
Posts: 576
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From: Placitas, NM
E550
Hmmmm . . . that's interesting.
In my car, Distronic Plus + Brake, I can clearly see the RPMs pop up as it shifts down on downgrades to maintain a CC speed, sometimes more than one gear if the first downshift doesn't do the job.
I've never had a downgrade where I thought the car applied brakes. Maybe with your scheme, a quick 15mph CC change, it would feel brakes are necessary.
?????????????????
In my car, Distronic Plus + Brake, I can clearly see the RPMs pop up as it shifts down on downgrades to maintain a CC speed, sometimes more than one gear if the first downshift doesn't do the job.
I've never had a downgrade where I thought the car applied brakes. Maybe with your scheme, a quick 15mph CC change, it would feel brakes are necessary.
?????????????????
Thread Starter
Junior Member
Joined: Jan 2012
Posts: 50
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2012 e350 wagon
I definitely have felt the brakes. It's like me -- it tries first to lift the throttle, and then applies the brakes.
The question is when the brake lights come on -- when it lifts, when it applies the brakes lightly, or only when it throws out the anchor? Watching the people behind me, it seemed like the lights were late (or the people were texting...)
The question is when the brake lights come on -- when it lifts, when it applies the brakes lightly, or only when it throws out the anchor? Watching the people behind me, it seemed like the lights were late (or the people were texting...)
Super Member
Joined: Apr 2011
Posts: 639
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From: Suburban Phila., PA
2012 E350 Coupe
FWIW and FYI, if a state in the U.S. has motor vehicle equipment requirements laws, and these days most if not all of them do, it would undoubtedly be illegal for the brakes to be applied - by any normal means - without the proper rear warning lighting equipment being simultaneously activated, as is the case in PA.
I doubt MB would design a system that worked counter to that.
The more I read posts about Distronic Plus, the more fascinated I am about this supurb technology. I don't have it, but buying my next car will take a bigger bite out of my wallet because of D+ or whatever it may be called by that time.
For those of you who have it, great choice!
I doubt MB would design a system that worked counter to that.
The more I read posts about Distronic Plus, the more fascinated I am about this supurb technology. I don't have it, but buying my next car will take a bigger bite out of my wallet because of D+ or whatever it may be called by that time.
For those of you who have it, great choice!
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Thread Starter
Junior Member
Joined: Jan 2012
Posts: 50
Likes: 3
2012 e350 wagon
FWIW and FYI, if a state in the U.S. has motor vehicle equipment requirements laws, and these days most if not all of them do, it would undoubtedly be illegal for the brakes to be applied - by any normal means - without the proper rear warning lighting equipment being simultaneously activated, as is the case in PA.
I doubt MB would design a system that worked counter to that.
The more I read posts about Distronic Plus, the more fascinated I am about this supurb technology. I don't have it, but buying my next car will take a bigger bite out of my wallet because of D+ or whatever it may be called by that time.
For those of you who have it, great choice!
I doubt MB would design a system that worked counter to that.
The more I read posts about Distronic Plus, the more fascinated I am about this supurb technology. I don't have it, but buying my next car will take a bigger bite out of my wallet because of D+ or whatever it may be called by that time.
For those of you who have it, great choice!
I have yet to have it apply brakes when not on cruise in an impending accident situation. I have had it beep at me several times when someone has cut me off.
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Joined: Feb 2010
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2015 GL450
The more I read posts about Distronic Plus, the more fascinated I am about this supurb technology. I don't have it, but buying my next car will take a bigger bite out of my wallet because of D+ or whatever it may be called by that time.
For those of you who have it, great choice!
Thread Starter
Junior Member
Joined: Jan 2012
Posts: 50
Likes: 3
2012 e350 wagon
That's an interesting point. There are several things ours spoils us with. Braking when on cruise...blind spot warnings, lane departure warnings and corrections. Great technology but it can make you lazy. Several times in our adventure car (Subaru Legacy) I've thought "odd, it didn't beep at me when that guy was in my blind spot and I indicated"...
