Service brake problems in wet weather

[dalexis]

Hello, been driving a 2015 freightliner cascadia and yesterday I had problems with the service brakes on the tractor just decide they would stop working. The brake pedal was stiff and extremely hard to push. There was a little bit of braking power present but not much and when I really stomped on the brakes it would pull to the left. The trailer brakes were working just fine through the trailer brake valve on the dash. When i started out that morning everything was working just fine, made my delivery at the lowe's store and headed out. The brakes worked just fine on the way out to the interstate. Traveled around 30 miles without touching the brakes but when I went to get off at my exit that's when I first noticed the brakes were not working properly. During this 30 miles or so it was pouring down rain. By just the way and how it happened i've been thinking this is more along the lines of an electrical or possibly a foot valve problem. Anyone else out there driving an freightliner having these same issues and can point me to the culprit?

BTW: the brakes were checked and they were not out of adjustment and they all appeared to be activating as they should. I have driven for nearly 16 years and have never experienced this sort of problem before. Pretty spooky when you try to apply the brakes and there is nothing there to stop you.