I Have noticed driving around that some (not all) SD 3rd brake light will flash a few times before it is constantly on. Is this a mod????? or a setting i can change????

 

Maybe the 2019's? I've noticed a lot of the newer vehicles now days have 3rd brake lights that quickly flash or strobe almost before going to a constant on.

It's probably for the idiot millennial's who can't pull their nose out of their snapchat for any period of time, let alone while driving.

 

My 2017 does it. Dealer installed it on all the cars they sold

 

https://www.ebay.com/itm/GS-100A-12V-LED-Brake-Stop-Light-Strobe-Flash-Module-Controller-Box-For-Car/182700403913?hash=item2a89caecc9:g:XNsAAOSw8TBZds9 F

 

I just found a brochure in my truck I hadn't noticed. It's called Pulse and the card says "we install Pulse on all the vehicles we sell"
Not sure I like it or not. I don't have to look at it, lol
I checked and it's definitely there.

 

More info

HTH,
Jim / crewzer