Charlie Fulbright

I have a 2017 GMC Sierra SLT 1500. It has just over 38,000 miles. Just recently when backing my boat down into the lake, my brake pedal began to have to be pushed almost to the floor to stop the pickup from rolling into the lake. A little scary to say the least. It has done it 3 times. Also I've already had GM's reflash of the brake controller done. I bought the extended warranty so hopefully it will be covered under that. Just know I don't want to roll backwards into the water!