[NFS]

Originally Posted by mjh93sa

Before this turns into another DTC / DSC thread

is your friend....

The article here suggests that a decceleration of 5m/s2 or more triggers the system. This would seem fairly sensible as you can brake quickly without using ABS. But I would have added the ABS activation as an additional trigger if I were designing the system as there is the possiblilty that you are unable to achieve 5m/s2, such as when braking on a slick surface.

The glossary here also states that a decelleration of more than 5m/s2 is required to trigger the BFD.

Nice work Matt.

Do you think we need a new DSC/DTC thread?

I miss the old one.

[mjh93sa]

Originally Posted by needforspeed

Nice work Matt.

Do you think we need a new DSC/DTC thread?

I miss the old one.

nah! ..... but it's about time we had another fridge thread

[ChrisMWard]

Originally Posted by mjh93sa

Before this turns into another DTC / DSC thread

is your friend....

The article here suggests that a decceleration of 5m/s2 or more triggers the system. This would seem fairly sensible as you can brake quickly without using ABS. But I would have added the ABS activation as an additional trigger if I were designing the system as there is the possiblilty that you are unable to achieve 5m/s2, such as when braking on a slick surface.

The glossary here also states that a decelleration of more than 5m/s2 is required to trigger the BFD.

This does sound much more plausible, as well as using the same sensing to activate the BFD.

Regards

Chris

[mjh93sa]

To add a little context:

5m/s2 equates roughly to 0.5g or 11mph/s acceleration. Various sources online suggest that a maximum braking force in the region of 1g can be achieved by current road cars.

Therefore the brake force display should cut in significantly before ABS on a good dry road.

[mmm def]

Here is the Motorweek 335i review. At the end they rip around a track and you can see the brake lights in action.

[E92-Mark]

Cool, so thats what it looks like

[mjh93sa]

Have they changed the way it works, or is the US coded differently?

I ask as the brochure shows only one half of the brakelight lit for normal braking and both for BFD on. However, the video above shows a much more sensible approach of putting every bit of red light on that you can in an "emergency" stop by using the foglights.

[Z4 Beemer]

I certainly thought that in the UK, on the E92 it was the fog lights that acted as the second stage. I could be wrong.

[mjh93sa]

I was thinking more of the E90/91. I've got no idea what happens on the E92.

From the photo below you can see that the standard braking illumination (of Beauforty's E90 at least) is only half of the light cluster mounted in the wing. Also, the photo posted by NFS shows illumination of the full cluster within the wing for BFD.

Given the video evidence from youtube posted by mmm def it would appear that one of three things is going on:

1. US spec cars are different to UK spec ones. (Euro nanny regs perhaps)
2. There has been a change to the system such that the foglight is now used.
3. It's actually a 3 stage system and the foglights come on with the ABS

WARNING! Do not attempt to check brake force display in shop window reflections... you'll get arrested for ram raiding if you get it wrong.

[ChrisMWard]

It used to be illegal to use rear fog lights as brake lights in the UK, as I found out years ago with one of my cars. Maybe this has changed now, but there are lots of different lighting regulations between US and UK cars.

Regards

Chris

[mjh93sa]

Originally Posted by ChrisMWard

It used to be illegal to use rear fog lights as brake lights in the UK, as I found out years ago with one of my cars. Maybe this has changed now, but there are lots of different lighting regulations between US and UK cars.

Regards

Chris

It would be rather interesting to compare a US spec car that has been SVO'd for the UK (like Floyd's or Marilyn's) and see if they have changed that if it is just a US/UK difference as they don't adjust the indicator as corner marker setting.

My inclination is that it probably is different, and that nanny EU regs are at play. For emergency stopping I see no probem with using the foglights as they woul be a real attention getter. Just a little more light area of the same intensity doesn't seem as strong an indication.

[NFS]

Originally Posted by mjh93sa

It would be rather interesting to compare a US spec car that has been SVO'd for the UK (like Floyd's or Marilyn's) and see if they have changed that if it is just a US/UK difference as they don't adjust the indicator as corner marker setting.

My inclination is that it probably is different, and that nanny EU regs are at play. For emergency stopping I see no probem with using the foglights as they woul be a real attention getter. Just a little more light area of the same intensity doesn't seem as strong an indication.

I know it probably doesn't help, but on the e46 coupe the fog lights were not used. Instead an additional area of the LED's lit up on hard braking:



Cars in the US don't have foglights (I believe) I'm wondering if the US cars display the full brake bar then use the foglight for the second stage.

In the UK we need the fogs and it would be confusing if they flashed on braking. Therefore we have a different 2 stage system.

The pick ksfrogman posted does not show the fogs illuminated - but it could be that the 2 stage system was not active in the picture ....

[booforty]

I love a bit of HARD braking every now and again... its great!

[mjh93sa]

As I was on bmw.co.uk playing with the configurator again last night I thought I'd email them to see what they had to say, and got a nice email today stating the following:

Thank you for contacting BMW Customer Information.

We can confirm that we are only able to advise on UK specification vehicles and that BMW introduce Brake Force Display as it was a simple yet effective way of communicating to following traffic that the BMW in front is stopping quickly, providing extra advance warning of a potential road hazard ahead. This should help lessen the need for harsh emergency braking by following drivers who now have extra reaction time.

We hope the adoption of Brake Force Display will lead to a reduction in avoidable rear-end collisions as well as help prevent loss of control caused by panic braking in vehicles not equipped with advanced electronic chassis systems such as BMW's Dynamic Stability Control.

We can advise that Brake Force Display in the UK works by increasing the intensity of the brake lights in the rear lamp clusters by expanding the number of illuminated LEDs when heavy braking is detected. The extra lighting is triggered after the anti-lock brake sensors detect a rate of deceleration in excess of 5 m/second². As an example of the force of the braking, at 5 m/second² a briefcase placed on a car seat would accelerate off the seat onto the floor. The system reacts within a few tenths of a second to increase the intensity of the stoplight illumination, projecting a highly visible warning beacon to following traffic. Only deceleration forces trigger Brake Force Display, not simply pedal pressure, in order to avoid unnecessary illumination.

We can confirm that UK vehicles would not show the fog lights in the boot lid being illuminated under heavy braking and can only recommend speaking to BMW USA Head Office for further comments, as to why the E90 BMW 335i on the video you have seen does that. Their contact details are detailed below:


Corporate Headquarters
BMW of North America, LLC
300 Chestnut Ridge Road
Woodcliff Lake,
New Jersey 07677-7731
P.O. Box 1227
Westwood NJ 07675-1227
USA

Tel.: +1-201-307-4000
Fax: +1-201-307-4095

That pretty much covers it - confirmation of the decelleration rate and that fogs are NOT used in the UK.

[NFS]

Originally Posted by mjh93sa

As I was on bmw.co.uk playing with the configurator again last night I thought I'd email them to see what they had to say, and got a nice email today stating the following:

That pretty much covers it - confirmation of the decelleration rate and that fogs are NOT used in the UK.

[red-max]

Originally Posted by mjh93sa

We can advise that Brake Force Display in the UK works by increasing the intensity of the brake lights in the rear lamp clusters by expanding the number of illuminated LEDs when heavy braking is detected.

So have we got LEDs for brake lights, or just LEDs for the extra brake force display? Is this true for both E90 and E92 - which did you enquire about?

[Z4 Beemer]

The e92 doesn't have LED's for brake lights? Where are the extra bits on the E92 for brake force display?

[Z4 Beemer]

Ok people, turn to page 120 of your E92 owners handbook.

Area 5 says "Rear fog light/two-stage brake light"

However, area 4 says "Brake light, consisting of two individual bulbs"

Image the left side lights on the car to be made up as follows:

4
3 5
2 6
1

where area 1 is the indicator and 3 is the reversing light.

2 and 6 are the LED tail lights which give the 3 line stripe effect.

Everyone clear on this

[mjh93sa]

I did specifically title the email E90/91 Brake Force Display, but I think that the gentleman who replied had things slightly twisted with the first cars to introduce this feature, which I believe were the E46 coupes. In these the brakelights were indeed LED, but are no longer in the E9x series. Tail lights are LED on the E92 as I was following one a few weeks ago with a dodgy connection to the bootlid section that kept flashing on and off, I don't know about the E90/91.

However, this aside the critical items that are confirmed are the decelleration rate and the fact that in the UK the foglights are not used.

The rest is almost directly from a generic BMW technology guide.

Z4... I'd get the manual out... if only I had one

[booforty]

Originally Posted by mjh93sa

As I was on bmw.co.uk playing with the configurator again last night I thought I'd email them to see what they had to say, and got a nice email today stating the following:



That pretty much covers it - confirmation of the decelleration rate and that fogs are NOT used in the UK.

Yes there is a GOD, and low and behold, he lives in Gloucester... who would have thought it....

[Z4 Beemer]

Ok, the brochure I have actually shows the fogs on where it talks about second stage braking... hmmm

[vivekk]

Originally Posted by mjh93sa

As I was on bmw.co.uk playing with the configurator again last night I thought I'd email them to see what they had to say, and got a nice email today stating the following:



That pretty much covers it - confirmation of the decelleration rate and that fogs are NOT used in the UK.

Unbelievable- a useful reply from BMW UK Customer Services- nice work Matt!

Viv