How to disable a brake chamber

No you didn't. It wasn't the slack adjusters or anything else on the wheel. It was that valve like @Cat sdp suggested.

 

Just a follow up. I've been home for a while. I knew the relay valve solved the problem but this morning at 2am I took my truck and trailer for a ride around town. I live in a small town in NH. I absolutely beat the crap out of the brakes. Stopping on a hill and releasing the brakes the truck and trailer started rolling down the hill. At a dead stop applying 100 pounds on the brakes multiple times. Hard stops. Locked up the brakes once, released and it went on it's merry way.

I now realize this is a problem that has slowly been getting worse and maybe started years ago. When something gives you a problem but starts real slow I think you tend to adapt to it without knowing there is a problem. You just live with it. I look back now on all the warning signs but you think about pulling into a shop. What are you going to tell them? It does this and that once in a while?

I'm using a LOT less air to come to a stop. And not bleeding air off while at a stop. My trailer ABS light is working again also for a few seconds when I turn the key on.

Thanks again to @Cat sdp. My mechanic is a little pissed at you. He said all the bearings on the arm that goes from the brakes to the slack adjusters needed to be replaced. When I did come home I demanded he replace the relay instead. He even told other people I was taking advise from people online.