A buddy of mine sent me this pic yesterday. This is a 2004 KW T800 day cab. I could probably get the VIN, but don't have it. He asked if I knew what the purpose of these air valves is, said that the lines were too bundled up to trace down. I circled the area he said was leaking air. My suspicion is it's a PPV, but usually those are on the tanks.
Looks like a dump valve. Scratch that, the dump valve is to the left.
That is a one way check valve {circled}
Any idea what that messes purpose is?
Those years, could be a multiple, but that type of electrical connection was/is common to ABS. Thinking back possibly part of traction control.