Air Leak.

No. You have a airleak in the trailer system or the maniford. OR your air system on the trailer is slow to fill.

 

Do you have auto inflate on trailer? Give it 5min to see if pressure builds up in trailer (not gauges). If hiss persists contact RS

 

You need to go ahead and push in the red trailer air valve then give it some time. In the mean time go out and listen for leaking air in the trailer somewhere. Hopefully you're just hearing the air bags re-inflating. This can take a considerable amount of air, but if after several minutes, you can still hear air movement "in the dash" through the valve, something is wrong and you should be able to audibly identify where you have some sort of rupture or leaking connection.

 

You need to do first things first.

1. get a full charge of air with trailer button out
2. press trailer button in
3. wait 3 minutes, do you still hear air moving through the valve?
   1. if so, go all around the trailer. You should hear air leaking or filling something. Don't worry about brake application air because that's not the immediate problem.
   2. is the truck compressor able to keep up [at idle] with the air loss? Can it reach the full pressure point where you hear the air dryer cycle? If not, and you can't identify where the air is being lost, then you may well need to consider getting somebody to come out.

 

Try wiggling the valve. Sometimes you can get a leak right there and wiggling it will stop it.

 

There's no air compressor under the sleeper. There are air tanks under the sleeper, but if they were leaking, you would hear it regardless of buttons in the cab you could push. Build your air pressure up to full, kill the engine and climb underneath and listen. You dont want to just go get service. You want to know EXACTLY what's leaking.

You said that you pushed the red valve in and put a stick on the brake pedal. The problem with that is, you dont know if the problem is on the tractor or the trailer. If you have a trailer hand brake, push the red knob in, pull the hand brake all the way down, and then walk around the trailer and listen. If you hear an air leak, my money would be on the trailer brake chamber (those pod looking things under the truck and trailer). There are 2 air lines going to each pod. One is for parking the other for service. What happens is when the brake chambers go bad, air will leak from one side of the chamber to the other. You will hear this leak in the dash.

If it is leaking from the parking brake side, remove the appropriate air line from the pod (if you listen and feel, you will know which one is leaking), put a dime in the hose and screw it back on. On the sides of the big brake chamber' you will see a bolt with a funny end. Take the little dust cap off the brake chamber and stick that bolt in and tighten it. It will cage the parking brake spring.
If it leaks when you pull the hand brake down, it's the service brake side. Put a dime in the hose. Then drive to a shop. And contrary to what the fearmongers may tell you, you're not doing anything wrong. They were made this way from the manufacturer so that you can get the truck to a shop.

"Am I doing anything illegal, Six?"

No, you are taking your truck to a shop for repairs.

 

Don't know where the op is.
If he has a froze up line on the trailer,air will leak at the red button sometimes.