When I let off brake peddle, trailer brakes still have pressure applied

Look unless you know what you are doing, just take it somewhere to get looked at where they know what they are looking for.

 

Wait! I'm still trying to figure out how you have 130 psi brake pressure on the trailer.

Is anybody actually reading the numbers or ya just skimming.

Go re read it and tell me the OP makes sense.

 

Say you're trying to read a pressure of 120 psi. To get the most accurate reading, you'd want to select a gauge capable of reading 250 psi max. The safety factor I guess wouldn't really be needed with air systems since worst case scenario it will only be 150 psi max.

 

After brakes have been applied and released take the glandhand of the blue line. Was there residual air pressure when you removed the gland hand? If so problem is with most likely with tractor protection valve. The one behind the cab with the red blue and red lines are on. In some cases the mv 3 valve can cause this also ( the one with the yellow and red button)

 

The safety factor is what got me. All the other stuff makes sense. But it doesn't make sense in this post. Not when he has 120-130 psi brake pressure. The dude is laying rubber with that.

Or he thinks his secondary air gauge is the trailer air.

I go with the latter since he said it stays the same at 130.

 

Yeah my head was thinking hydraulics for some reason.

 

One is primary tank one is secondary not trailer