One problem related to brake hoses, lines/piping, and fittings has been reported for the 2015 GMC Yukon. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2015 GMC Yukon based on all problems reported for the 2015 Yukon.
Power breaking fails when driving at low speeds, brake pedal stiff and hard to push down to stop vehicle in both forward and reverse directions when inching forward at a stop light/sign, or parking in a parking lot in forward and reverse car keeps moving. Stopping required very hard push on the stiff brake pedal. . Braking at higher speeds less affected but sudden stops can require more force than usual as the car slows down. Problem began December 2017 rarely and intermittently, and increased to all the time by February 2019 at low speeds the power brake did not work and required much force on the brake pedal to stop vehicle every time. Brake fluid was fine and so was brake pads. Gm dealership visit showed a failure of the vacuum pump for brake line and they installed a redesigned pump which shows that the original has faulty design. They also required a belt that operates pump to be replaced as well. This seems to have fixed the problem for now but this repair has a two year guarantee. Price for me to fix over $881+tax.