The brakes on my GMC Sierra 1500 lose braking power when operating at slow speeds. The brake pedal will lose braking power, causing the vehicle to not stop at slow speeds. This is particularly troubling when pulling into and out of parking spots, driveways, crosswalks, and other areas. I use my truck to pull a boat and when I back my boat into the water at a boat launch, the brakes will lose power when I am in reverse causing the truck to slid into the water.