Service brake problems in wet weather

[Sergiu]

Maybe some moisture got inside your ABS relay valves' electrical connections they are very sensitive, a new valve solenoid will show only 4-7 Ohms of resistance, everything else is out of spec and may influence your braking.
P.S. not related to your problem but could help somebody:
On my 2012 cascadia -- two abs valves under the fifth wheel has been leaking air only when tractor brakes were released, I thought it could be worn o-rings, seized valves/electronic actuators or bad programming. I decided to go for 1 year warranty on a new part (two abs valves and relay valve), freightliner parts guy told they change those all the time, seems something usual for 2012 cascadia, didn't have this issue once on my 2010 peterbilt though. Today I replaced that part and still was losing air until I found that two of my brake chambers had an internal leak. The air is leaking through the center near pushing rod from the spring brake side, and going back up the service line and out the exhaust of the relay valve. I took off the service line from each maxi one by one to find the culprit. Changed defective brake chambers and everything is working properly. BTW my truck was pulling to the right all the time, three alignments didn't solve the issue, also brake shoes on the passenger side was thinner then those on driver's side. The reason was internal leaking defective brake chambers.