I did a bit of research due to a soft pedal on our 2013 Edge. It seemed everything I found was a hit and miss. Many people that had replaced the master cylinder said it worked for a short time then reoccurred. There was no logic to it being the Booster and that had been replaced due to a recall. No loss of brake fluid. I tried the driving about 25 mph and standing on the brakes, it didn't help. The more I researched the more it seemed to be the HC unit for the ABS. I looked at replacing it with a rebuilt unit and the cost, the down time of the vehicle and my labor just added to my frustration. I found a reasonably priced bi-directional scanning tool, about $180, so if it didn't work, I had a tool that I could use for other vehicles too. I scanned for codes, and nothing came up for brake issues. I did clear any other codes. I then started cycling the through the ABS HC unit for each caliper. I could hear the HCU each time I cycled it. I repeated this about 3 times. I took it for a drive, and it still had a soft pedal. So, I did the driving about 25 mph and standing on the brakes, and I could feel that the pedal was firmer, so I did it one more time, and that, so far, has remedied the problem. I did this about 3 months ago, so far so good.
Rare
Rare
Rare