It's called Pulse. When I bought my Kia up in MN, the sales guy met me at the door and said "We accidently installed Pulse on your car and it unreversible but I know we had a set price so there is not going to be a charge". My understanding is that it's basically a $30 box spliced into your brake wires that the dealers try to charge between $300-$600. If you haven't used the brake within the last 5 seconds, it will flash(Just 3rd light) 4 times but then if you continue to use the brakes, it will just act normal until there is a 5 second gap again.When I bought my last car two years ago, one of the cars I looked at was a GM car. They tried to upsell me on a feature that would flash the brake lights intermittently when you took your foot off the gas, thus warning those behind you that you might brake. This was a monthly subscription. In the past two years, I only seen this on the road 2 or 3 times.
I wouldn't pay 5 cents for it and wish is wasn't even on my car. I don't want other drivers thinking that I was dumb enough to buy it.