No brake lights? Why not?
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Joined: Apr 2007
Posts: 213
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From: SF Bay Area
2015 GLK 250 BT
No brake lights? Why not?
I just realized that when we turn off our engines, ie. key switched off, that our rear brake lights can NOT be activated. What? Why not? Does this bother you folks?
On any other "normal" cars (without SBC), the brake lights can still be activated by depressing the brakes. In our E-Class, W211 with SBC, the brake lights are disabled with the key off. This seems wrong. There are times that I would want this feature, ie. parked somewhere with the engine off and foot on the brake to show that I'm stopped.
On any other "normal" cars (without SBC), the brake lights can still be activated by depressing the brakes. In our E-Class, W211 with SBC, the brake lights are disabled with the key off. This seems wrong. There are times that I would want this feature, ie. parked somewhere with the engine off and foot on the brake to show that I'm stopped.
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From: Irvine, CA
2008 E550, 2012 GL450, 2014 GLK350, 2015 S550, 2020 GLC350e
Well, I have a 2008 E550 (no SBC) and the brake lights dont work with the engine off either. I haven't checked in it works in either of the two accessory modes.
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From: Europe
223.168 & 213.012 & 906.633 & 214.005
I tried it too, when I switched off the ignition, even if I did not take the key off, got no brake lights (electronic control units would not have gone to sleep yet). This was a W221 too. Your observation has nothing to do with SBC.
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From: Ft. Lauderdale Area, USA
2015 ML 350
Its probably because there isnt a direct connection between the brake light switch and the rear lights. Closing the brake light switch probably is like a mouse click to the cars computer system, telling it to turn on the brake lights. No power to the computer = no response from the mouse click.
Did you ever notice that when you very quickly momentarily press the horn, there is a delay before the horn sounds? If you are really quick to tap, the horn will never sound at all. Probably the same mouse click thing.
While we were parked in a Bank's lot I sat in my Pop's 210 & watched as a woman came within 1/2 inch of backing up & swinging her front fender into his door while I was ferociously pounding on a non responsive horn button. In his 210, when the car is shut off, his horn doesn't work either.
The computer has to controll all this stuf or how else could it tell nearby bulbs to substitute for important bulbs that are burned out...
Just an educated guess.
Did you ever notice that when you very quickly momentarily press the horn, there is a delay before the horn sounds? If you are really quick to tap, the horn will never sound at all. Probably the same mouse click thing.
While we were parked in a Bank's lot I sat in my Pop's 210 & watched as a woman came within 1/2 inch of backing up & swinging her front fender into his door while I was ferociously pounding on a non responsive horn button. In his 210, when the car is shut off, his horn doesn't work either.
The computer has to controll all this stuf or how else could it tell nearby bulbs to substitute for important bulbs that are burned out...
Just an educated guess.
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Joined: Dec 2006
Posts: 6,497
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From: Europe
223.168 & 213.012 & 906.633 & 214.005
Its probably because there isnt a direct connection between the brake light switch and the rear lights. Closing the brake light switch probably is like a mouse click to the cars computer system, telling it to turn on the brake lights. No power to the computer = no response from the mouse click.
Did you ever notice that when you very quickly momentarily press the horn, there is a delay before the horn sounds? If you are really quick to tap, the horn will never sound at all. Probably the same mouse click thing.
While we were parked in a Bank's lot I sat in my Pop's 210 & watched as a woman came within 1/2 inch of backing up & swinging her front fender into his door while I was ferociously pounding on a non responsive horn button. In his 210, when the car is shut off, his horn doesn't work either.
The computer has to controll all this stuf or how else could it tell nearby bulbs to substitute for important bulbs that are burned out...
Just an educated guess.
Did you ever notice that when you very quickly momentarily press the horn, there is a delay before the horn sounds? If you are really quick to tap, the horn will never sound at all. Probably the same mouse click thing.
While we were parked in a Bank's lot I sat in my Pop's 210 & watched as a woman came within 1/2 inch of backing up & swinging her front fender into his door while I was ferociously pounding on a non responsive horn button. In his 210, when the car is shut off, his horn doesn't work either.
The computer has to controll all this stuf or how else could it tell nearby bulbs to substitute for important bulbs that are burned out...
Just an educated guess.
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From: Longmont, CO
04 E320 4 Matic, 95 Audi S6, 99 Carrera 4 Cabrio, 12 Fiat 500 Sport, 00 BMW R1200C 10, BMW R1200R
A similar thing happens with the Reverse Lights. It seems that they don't come on until a few seconds after the car is in reverse. Usually, you see cars blink the reverse lights for a millisecond when you shift out of park and pass through reverse on the way to drive.
The W211 (and I suspect other MBs too) never blink their reverse lights anymore. It could be that it only turns them one once the car is actually in reverse (as in the transmission) and not when the gear selector is in the R position.
Just an observation,
Steve
The W211 (and I suspect other MBs too) never blink their reverse lights anymore. It could be that it only turns them one once the car is actually in reverse (as in the transmission) and not when the gear selector is in the R position.
Just an observation,
Steve
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Newbie
Joined: Oct 2007
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From: sacramento, california
2006 e-350 and 2006 ml350
there are alot of cars that the brake lights stop working with the key off. it's called power moding. it's when a module controls a system, and must be powered up to work. older cars ran the brake lights right off the switch, now bcm's and several other modules are used.
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Member
Joined: Nov 2001
Posts: 216
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From: Albuquerque
2003 E320
I know nothing about BMWs but it is the way Mercedes has always been (or at least for a long time). I just went to the garage and checked my three Mercedes. None of the brake lights turn on unless the key is on. That is on a 1966 230SL, a 1999 SLK230 and a 2003 E320.
