Do the brake lights come on when the regen is in operation?

[Pannett]

I am asking the question because our Octavia PHEV used regen braking with cruise control on to hold the set speed. It was on a night drive that I saw the brake lights reflected behind me on road signs. This must have been annoying for following vehicles as the brake lights would switch on and off a lot, even if there was a flat road or a slight incline. Obviously there is nothing I can do about it if the Toyota's brake lights do come on, but at least by looking at the regen meter, I can see that it doesn't happen as often as it did for the Octy.  I also use the handbrake if I'm stopped at lights, just in case the brake lights stay on with autohold: they can be bright and annoying, particularly at night

[Chippy01]

I have noticed on my Corolla Cross that under gentle/medium slowing when using the adaptive cruise, the brake lights do not illuminate.
However, if the braking becomes what might be classed as heavy, again while using the ACC, the brake lights will light up.
I can only assume there is something that monitors the deceleration force, and that is linked to the brake light system.

[Roy124]

Phil,  I read, on here I think, that there are specific deceleration figures that determine whether they light up or not. 

Failing a g meter your suggestion fits the bill.

[Extreme_One]

I'm pretty sure in the Corolla it depends how much deceleration is needed.

If the cruise control decelerates at a similar rate than could be achieved by simply lifting off the gas there will be no brake lights, but heavier deceleration which would involve use of the brake pedal if it were you or I controlling the speed then the car's brake lights will come on.

[fred88]

Agree with the above, it comes down to - does adaptive cruise actually apply the brake or does it rely purely on engine braking? If it does apply brakes then I would have thought the brake lights would come on then but not during engine braking?