Warning light added to show when the brake lights are on.

[MG Clive]

Why? you may ask, well there has been so much discussion about when, and under what circumstances the brake lights come on, so I wired a small light into the brake lights to check for myself.

I found this so useful that I've now made it a permanent feature in my car, I just glance in my rear view mirror when braking, decelerating, or just lifting my foot of the accelerator, and I see the red led in my mirror.

This is the position of the light.


So I can tell you that the brake lights come on when:
You apply the foot brake (obviously).
You apply the EPB, either while stationary or moving.
When you're stopped with autohold on (foot on or off the brake pedal).
In maximum regen, if you lift your foot fully and quickly off the accelerator pedal, the brake light comes on immediately, if you lift your foot off the accelerator pedal slowly, the brake light comes on after a few seconds depending on your initial speed, if you lift your foot off the accelerator pedal very very slowly and gradually, you can get down to the 5/6mph crawl speed without the brake light coming on, but it's very difficult to do.
In Medium or Low regen, the brake light doesn't come on at all when decelerating.
OPD works in pretty much the same way as full regen, but because the car comes to a full stop using OPD, the brake light comes on when fully stopped.

 

[Caramaddy]

Why? you may ask, well there has been so much discussion about when, and under what circumstances the brake lights come on, so I wired a small light into the brake lights to check for myself.

I found this so useful that I've now made it a permanent feature in my car, I just glance in my rear view mirror when braking, decelerating, or just lifting my foot of the accelerator, and I see the red led in my mirror.

This is the position of the light.
View attachment 39521

So I can tell you that the brake lights come on when:
You apply the foot brake (obviously).
You apply the EPB, either while stationary or moving.
When you're stopped with autohold on (foot on or off the brake pedal).
In maximum regen, if you lift your foot fully and quickly off the accelerator pedal, the brake light comes on immediately, if you lift your foot off the accelerator pedal slowly, the brake light comes on after a few seconds depending on your initial speed, if you lift your foot off the accelerator pedal very very slowly and gradually, you can get down to the 5/6mph crawl speed without the brake light coming on, but it's very difficult to do.
In Medium or Low regen, the brake light doesn't come on at all when decelerating.

This is exactly the same as my MG5 PFL SR - Last year I had a software update and the Level 3 regeneration/braking effect is not as severe as it was at first.

 

[siteguru]

I'm surprised that using the EPB (i.e. pulling up the lever) applies the brake lights ... unless it only does this when you're still moving. After all it is the equivalent of using a handbrake.

I can understand there being no brake light in regen 1, but I'm surprised that regen 2 doesn't put it on.

 

[MG Clive]

I can understand there being no brake light in regen 1, but I'm surprised that regen 2 doesn't put it on.

Yes I thought medium regen (2) might have put the brake lights on, but it didn't under any circumstances. This was on the XPower of course, others may be different.

 

[MG Clive]

If anybody is interested, it's just a pre-wired rubber T10 / 501 bulb holder with a red 501 LED bulb, mounted into the access grommet, and wired into the high level brake light.


And this is my 'test rig', well it's a mirror screwed to the back gate so that I can see the brake light coming on when my new light comes on.

 

[Everest]

Looks good... though, if one was to be really nerdy... then, technically, front facing lights should only be white or yellow

Colour of light shown by lamps and reflectors
11.—(1) No vehicle shall be fitted with a lamp which is capable of showing a red light to the front, except–
(a)a red and white chequered domed lamp, or a red and white segmented mast-mounted warning beacon, fitted to a fire service control vehicle and intended for use at the scene of an emergency;
(b)a side marker lamp or a side retro reflector;
(c)retro reflective material or a retro reflector designed primarily to reflect light to one or both sides of the vehicle and attached to or incorporated in any wheel or tyre of–
(i)a pedal cycle and any sidecar attached to it;
(ii)a solo motor bicycle or a motor bicycle combination; or
(iii)an invalid carriage; or
(d)a traffic sign.

 

[salty]

Looks good... though, if one was to be really nerdy... then, technically, front facing lights should only be white or yellow

Yeh but brake lights are Red.

 

[siteguru]

Yeh but brake lights are Red.

... but brake lights don't face forward.

Given that it is inside the cabin then I doubt anyone really cares.

 

[Everest]

Given that it is inside the cabin then I doubt anyone really cares.

Exactly... otherwise 99% of HGV's would be impounded

 

[OriginalBigAl]

Nice work , but on one of those dark and stormy Yorkshire Moors nights ..... close encounters of the third kind?...... sort of vibe. Now that's implanted in your mind....
Similarly if you happen to have a bald headed rear seat passenger in the middle you are going to confuse any following driver.

 

[MG Clive]

Looks good... though, if one was to be really nerdy... then, technically, front facing lights should only be white or yellow

It probably faces downwards more than forward, but it works for me, and it's only a 501 bulb, so I could change it for any colour I fancied.

 

[tsedge]

I'm surprised that using the EPB (i.e. pulling up the lever) applies the brake lights ... unless it only does this when you're still moving. After all it is the equivalent of using a handbrake.

To me this is a fault with traditional handbrakes. Why should there be a brake I can pull that doesn't put on the brake lights?!

Also consider the emergency braking if you pull the handbrake and hold it.

 

[siteguru]

#1 It was always suggested that when sitting at traffic lights one should apply the handbrake to avoid blinding the driver behind at night with your brake lights. So no, that wasn't a fault with traditional handbrakes

#2 I agree that applying the "handbrake" whilst the vehicle is in motion should cause the brake lights to activate, but not when the vehicle is stationary. The "in motion" part was probably a fault/omission with traditional handbrakes.

 

[tsedge]

#1 It was always suggested that when sitting at traffic lights one should apply the handbrake to avoid blinding the driver behind at night with your brake lights. So no, that wasn't a fault with traditional handbrakes

Brake lights should never blind, that's a design flaw if they do. At least, this is my view.

 

[siteguru]

High level brake lights make it worse.

 

[Everest]

Brake lights should never blind

Agree. Blinding the driver behind is the function of the rear fog light, not the brake lights

 

[Tuareg]

Is someone is 'blinded' by brake lights then maybe they should have an eye examination and even maybe not have a driving license at all.

 

[Alb]

I don't think the word blinded is being used in its literal sense. Dazzled would perhaps be a better description.

 

[MG Clive]

Sitting in traffic or at traffic lights on autohold puts the brake light on anyway, and I'd think this is the same on any vehicle with autohold, and this isn't really any different to sitting with the handbrake, or EPB on.

Anyway, the main reason for this is to see when the brake lights come on under regen, and I forgot to make any observations while using One Pedal Driving, so I'll do this later.

 

[crispyjay]

Is someone is 'blinded' by brake lights then maybe they should have an eye examination and even maybe not have a driving license at all.

If someone can’t put a handbrake on properly (not use auto hold) and take their foot off the brake then maybe they shouldn’t have a driving license at all.