I had a 2013 Lincoln MDX with 131,000 miles in the shop today and repaired the same Customer Concern soft brake pedal.. I did not replace the master cylinder, or the A.B.S. valve block, or pull the battery multiple times.. Now I'm home after work and Googled on the KZfaq... Your video was the first to Pop up.. Your final diagnosis of a stuck valve in the A.B.S. block was probably correct.. I performed the auto bleed procedure and the pedal may have felt slightly better?.. Before condemning, or falsely diagnosing a faulty master cylinder,, pull all 4 wheels and remove the mounting bolts from the brake caliper's.. Be sure that none of the sliding bolts or bushings are seized.. Crack open the bleeder screws "just gravity bleeding" and look for air bubbles.. NOW HERE WAS THE FIX!!.. Get another person to help on the brake pedal and manually bleed the flush the brake fluid system.. When I bleed the Left Rear caliper,, the brake pedal felt normal, and as good as new... Moral of the story is "Flush the brake fluid, because one of the valves is Stuck in the Muck!"

I left a comment yesterday, and called one of my best friends.. He's a retired Ford Master Technician.. He told me "Flushing the brake fluid was the best thing I did" Auto Bleed and Manually Bleed all 4 corner's.. The best place to start is Cover The Basics 👍

Great video, very clear as to what to do step by step! Thank you very much

On my 2013 Ford Edge sometimes the brake pedal will go soft after a hard braking event. Running the auto bleed function in Forscan always solves the problem...until the next hard braking event. Hopefully, flushing and bleeding at the four corners will prevent the problem from recurring.

UGH, I'm getting ready to do the same thing. Now I know what i'm in for.

Did you by chance look into disassembling the ABS module to look for stuck valve?