On page 107 “Driving” for the DS7 is clearly states “The resulting deceleration of the vehicle
does not cause the brake lamps to come on” yet when I’m driving at night I can see the high level brake light coming on every time I take my foot off the accelerator, anyone else notice this and is it a fault? Is the car using the brakes rather than the electric motor to slow down?
That’s a good one and never really noticed it.
I doubt the brake light switch is linked to brake pressure, Typically nowadays its a mechanical switch activated by the brake pedal.
My understanding is the lights only illuminate automatically when the cruise control is activated and not under normal regen. There is a legal requirement that specifies at what anount of adeacceleration the brake lights should be activated.
Yeah it’s a strange one Stu, couldn’t believe it when I saw the lights coming on approaching a slip road then again coming up to a roundabout, never touch the brake pedal yet the lights came on. Knew I’d seen something in the manual about it so looked it up and there it was on page 107 - not the only issue I have with my year old DS7 TBH
Were you in “B” mode ? Just wondering if that has a different behaviour to normal drive mode due to more agressive regen braking it has. I’ve not noticed any spurious brake lights coming on mine, but I’ve not been looking out for it. Adaptive cruise control is memtioned in manual as can activate the brake lamps (there are others - hill descent, etc - but don’t sound likely here).
Isn’t B mode what this entire topic is about?
There’s no regen braking without B mode, unless you actually press the brake pedal, which obviously will trigger the brake lights.
Yes Andy, has to be in B mode as Jay says, brake light come on as soon as I take my foot off the accelerator without touching the brake pedal - not a massive issue but when the manual says it won’t happen then it shouldn’t happen. Anyone driving behind me must think I’m a maniac on the brake pedal every 2 seconds lol.
True - I didn’t figure that the original question was specifically about when in B mode.
From observing the live energy flow schematic, it looks like regen can happen without the brake pedal in normal “D” mode - e.g. going downhill it displays green energy flow from wheels into traction battery even when not pressing brake.
I do not have that in my DS7.
Could it be either model specific, or perhaps newer models could have a setting for one pedal driving for example?
Yes Jay, I have a 17 month old “e-EAT8 electric automatic gearbox (Rechargeable hybrid)” Don’t see a setting for one pedal driving though.
Just noticed last night that the high level brake light shines off the rear screen wiper so it was quite easy to see, it was coming on EVERY TIME I took my foot off the accelerator EXCEPT when I got into my street and drove into my driveway so guessing under 5-10mph it doesn’t come on - think I might need to get this looked at especially if no one else has this issue.
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Because it’s not available in hybrids. It’s only available in EVs like the DS No8.
I googled it, and this is what Google AI has to say:
In your DS 7 Hybrid, the brake lights will automatically come on when the vehicle’s deceleration (slowing down) reaches a specific, government-mandated G-force threshold. They do not illuminate if you are just gently lifting off the accelerator, but will trigger when decelerating rapidly in ‘B’ (Brake) mode.
Here is exactly how the system determines when to turn them on:
Gentle deceleration (No brake lights): When you slightly lift your foot off the accelerator in ‘B’ mode, the car coasts or applies mild regenerative braking to recover energy. The brake lights will not come on.
Strong deceleration (Brake lights ON): If you take your foot entirely off the accelerator, ‘B’ mode aggressively uses regenerative braking to slow the vehicle down quickly. Because this deceleration exceeds a certain rate (negative G-force), the car’s computer will trigger the rear brake lights to warn drivers behind you, long before you physically press the brake pedal.
The AI has its own thing, and the manual states that energy recovery in mode B doesn’t activate the brake lights. There’s nothing there about the brake lights being activated when the recovery is greater.
The second option is that maybe in the 4x4 version there is a stronger regeneration with a G delay, because there are two electric motors, but the manual does not mention it and the brake light turns on.
The third option is a fault that needs to be checked and repaired.
Now that makes a lot of sense, DS need to update their handbook then as it clearly states the brake light will NOT come on.
Also, I’ll need to learn to drive again as every time I don’t want to accelerate either in traffic or at junctions but to slow down gradually I lightly take my foot off the accelerator, must be taking my foot off completely as the brake light comes on every time (apart from under 10mph) so DS haven’t quite got it right IMO.
I fear option 3 is the right answer Andrew, however I had my car into my local DS dealer for a check on the poor battery performance and they threatened me with a £176 bill if they find nothing wrong (Which inevitability they would) so I never bothered, I will wait and get the battery sorted under warranty if it fails.
Won’t be putting the car in to check the brake lights just to be charged £176 and told what Google AI said, will keep an eye on it and have everyone behind me panicking with the constant braking 
I had my car into my local DS dealer for a check on the poor battery performance and they threatened me with a £176 bill if they find nothing wrong
You’re lucky.
My local dealer charges me 300 euro to investigate, regardless whether they find anything or not.
So my repairs always cost = repair cost + 300
Shocking - Merc & BMW prices without the quality and reliability 
My Merc mechanics was actually cheaper than the DS shop.
Had two Mercs consecutively before this DS.