Trailer brakes won’t release

Your diagphrams between the springs and the service side inside the chamber might be a problem on each brake back there.

have you been draining that wet tank every night? If you havent and drain out 5 gallons of muck today that is where the problem is.

Double check your buttons in the cab to be sure they are both pushed in. And take another look at both of your glad hands. You say the trailer holds air, that seems ok. But it should release.

Ive forgotten the finer details but between the trailer tank of air and the service lines that go to each chamber needs to be looked at. If you are not loading each of those little chambers to release the springs you are not going anywhere.

Edit maybe chalk the stroke rods. They may be releasing but are so far out of adjustment them pads stay put lol.

The only other thing is this is still winter. The pads might have frozen to the drums back there and will not release until summer when it gets hot enough to do it.

 

The air exhaust line comes out of the firewall under the hood by the steering column. Make sure that's not plugged up with something. I had the same thing happen on my 90 and took a heavy piece of wire and pushed it up into the exhaust tube to clean it out

 

Ok you are causing me to consider inside your dash.

I am not the man to talk to about airlines inside your dash.

To me one of the glad hands should be blowing air but if it isnt like you say, the problem is the tractor I think.

It's really hard for me to consider a problem with a truck without being there in person and thinking it through.

 

Disconnect the red gladhand. Push trailer valve in and see if air comes out of hose connected to truck. If it don't, your problem is in the truck. If it does. Reconnect gladhand and disconnect blue hand. Pull trolley valve and see if air comes out from trailer.

Here's a stupid question which actually isn't.

You sure you got the gladhands connected to trailer correctly and not reversed????

 

The trailer doesn’t know whether you have applied the service brakes with the hand valve or foot valve. The trailer service relay valve merely gets an air signal from the tractor through the service line (blue if colored) regardless of how you apply the brakes. In other words unless the brakes are not releasing with both the foot valve and hand valve the trailer brake system likely is not the problem.

Why do you believe the hand valve is good?

 

Oh and btw check the exhaust line on the valve. If they are colored it’s usually the black one. Just disconnect it and apply and release the brakes with the hand valve. If no air comes out it’s a bad valve. If air comes out then the exhaust line is plugged.