Pulsing brake lights on new vehicles

[RossABQ]

For many years now (say 10 or more) I have seen what appear to be brand new cars with the high-mounted brake light pulsing, while the main brake lamps do not, at a rate of maybe once per second when the brakes are applied. This pulsing seems to stop after the cars are a month or two old, or maybe it's a mileage thing. I've also seen some (but much fewer) relatively new cars do this, making me wonder if they were just reset, i.e., new PROM or ECU, something like that.

Please tell me I'm not imagining this! and what purpose it serves? Some kind of study? To tell you the truth, I like the idea of pulsing HM lights, but if all cars did it all the time, it would get annoying pretty quickly in heavy traffic.

 

[IRstuff]

There was some discussion many years ago that pulsing brake lights could potentially avert some rearend collisions, by making it harder for the second driver to miss the brake light activation, perhaps as a by-product of inattention blindness.

However, whatever benefits there might have been, it's potentially swamped by the fact that people tend to use their brakes as turn signals, and often brake for no reason whatsoever.

TTFN
faq731-376

 

[SomptingGuy]

Brakes are for losers anyway. People who cannot anticipate or plan ahead.

Ambulance chasing lawayers would have a field day if a rear-ender cited flashing lights causing an epileptic fit as the cause of an accident.

- Steve

 

[patprimmer]

I pump the pedal anyway if the guy behind is not paying attention.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[benta]

In Europe, new cars with LED brake lights will pulse 5 times a second in an emergency braking situation.
This is a signal to the driver behind you that he should stand on the brake as well, instead of just "touching it lightly".
I'm not certain if the acceleration sensors are used for this, or the ABS control.

Benta.

 

[RossABQ]

I'm familiar with the concept of increasing pulse frequency with deceleration rate, and aftermarket motorcycle brake lights that pulse rapidly, but I've never seen anything about the OEM's running a test like this. I was hoping someone here would have heard about it.

 

[IRstuff]

Supposedly, there are a number of after-market OEMs for pulsed brake lights:

http://www.pulseprotects.com/

http://pulsingbrakelight.com/

One website does imply that pulsing lights were abandoned because of complaints.

TTFN
faq731-376

 

[MiketheEngineer]

Agree with all above - but what about having a "green" light that indicates you are accelerating and maybe a yellow light indicating you are lightly tapping the brakes??

 

[RossABQ]

My other question would be, since this pulsing ocvcurs when the vehicles (appear to be) brand new, how could they control the feature's turn-off? I've looked at a Chevy wiring diagram, and I'm not seeing any connection between the HM brake circuit and the body control module.

 

[IRstuff]

I don't recall ever seeing pulsing brake lights on the road.

Again, it's likely that the drivers of such vehicles get complaints, and go to the dealer to get it turned off.

The other issue, particularly for somewhat older vehicles is that the top brake light was still using incandescent bulbs, which would quickly burn out with that much pulsing.

TTFN
faq731-376

 

[RossABQ]

The behavior I recall was that on initial brake application the 3rd light would pulse, but as the vehicle slowed to a stop it would change to constantly on. If it only did this for the first month or so of a vehicle's life I'm sure the impact to bulb life would be negligible. It was not irritating either, because it pulsed pretty slowly.

I can't believe no one else has seen this?! Could it have been a regional test?

 

[Compositepro]

I saw this for the first time yesterday on a small pick-up that was not very new. I assumed it was some after market product.

 

[benta]

Funny.
This whole discussion revolves around something where nobody knows where it happens.
For all I know, the OP might be in Tasmania...
Probably, her/his observations were made in the USA, which everyone knows is the centre of the world. But perhaps not.
I posted about European cars earlier, but that was most likely irrelevant.

Well....


Benta.

 

[berkshire]

There was an attachment that pulsed a white strobe light in the brake light some years ago, thankfully it appears to have not cought on.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[RossABQ]

I was talking to a car parts wholesaler today and he may have the answer. He says the local dealers were installing pulsers on new cars and newer used cars in the same fashion as they used to sell "poly razzmatazz" paint sealants for added profit. They were charging a couple of hundred bucks for adding the module. He said the modules rarely lasted 6 months before burning out. That would explain why I haven't seen any older cars with them.

 

[patprimmer]

So the answer is shonky car dealers. Whoda thought, especially in Tasmania.

benta

Although USAans are the biggest single group here, they are still well short of a majority, so you are correct to wonder what jurisdiction and traffic laws might apply. I get accused of Yank bashing and even offend some people who I hold in high regard if I suggest that some from the USA unreasonably expect us to automatically know this.

It is quite a while since GM sold anything with a Chevy badge in Tasmania, so the fact that RossABQ refereed to a Chevy wiring diagram is a reasonable indication he is not from Tasmania or anywhere else GM does not sell Chevy badged cars. I guess that leaves the Americas and the Middle East as possibilities. Maybe parts of Africa?

Anyway, problem solved, no matter where in the world he is.



Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[IRstuff]

Given that the OP has been posting with US-related topics, coupled with mentioned items rarely found outside of the US, it was a reasonable assumption that he was located in the US.

TTFN
faq731-376

 

[RossABQ]

Benta's comment has merit. I've seen similar comments before and should have clarified.

I saw a piece buried in the back pages of the newspaper to the effect that a 20-year study of the impact of high-mounted brake lights on the rate of rear-end collisions in the US was... ZERO. As I recall, the study was conducted by the Insurance Institute for Highway Safety, who had previously (before the reg's became mandatory) estimated a 50% drop in rear end collisions. Counter-intuitive, but if we were totally data-driven, wouldn't that argue for a repeal of the regulations?

 

[dgallup]

I expect the rise of the cell phone (& subsequent texting) with it's attendant driver distraction may have more than offset any benefit brought about by the CHMSL.

This begs the question, why not eliminate turn signals since nobody uses them anyway?

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[benta]

The point of high-mounted brake lights is that you will (theoretically) see not just the brake lights of the car in front of you, but also the lights of cars further ahead (through the cabin windows).
However, as the odds are that the car in front of you will be a Ford F650 or some other monstrosity, the safety effect is cancelled.
(some sarcasm here...)

Benta.