Trailer brakes not working

Pull your blue line and make sure it's working when you apply hand brake. Trash could have got in air line on trailer too

 

Get under trailer and find service brake valve its the one that the brake lines lead to small chamber close to slack adj. and find part num. off of it and buy a new valve not rebuilt one?

 

One of my trailers did that. Its a thing with a plunger that get jammed up. Kind of like a brokern totlet bowl. If you get air pressure from the blue line when you step on the brakes then its that value where all the airlines connect to under the trailer.

 

Step 1, release the trailer brakes, then remove the blue gladhand from the tractor. Apply the service brakes and make sure that you are getting service air from the tractor. Then you'll know if it's a tractor or trailer issue.

If the tractor is not giving service air to the trailer, start by checking the tractor protection valve.

If the tractor is giving service air, check that the trailer air tanks have pressure. The spring brakes releasing does not mean you have air pressure in the trailer tanks. If the check valve is stuck in the spring brake release valve, it will release the brakes, but not fill the tanks. If the tanks are empty, it's most likely a sticking check valve in the spring brake release valve.

If the tanks have pressure, then pull the service line off the trailer relay valve (the one that goes to the blue gladhand) and step in the brakes to make sure that the line is clear and putting pressure to the relay valve. If the line is clear, you most likely have a bad relay valve.

 

Would this cause it to take a very long time to release the brakes after popping the red button even for a minute?

 

yes

 

I'n not 100% sure what you're asking. When you push in the red button, the spring brakes take a min to release? If the check valve is stuck closed (not filling the trailer tanks at all), then the spring brakes will release normally (assuming that the check valve is the only issue with the spring brake release valve).

Think of the spring brake valve being a Tee. Air from the red button goes in the middle, one side goes to the spring brake chambers and the other side goes to the air tanks (through a check valve). So a stuck closed check valve will not stop the spring brakes from releasing. If air cannot get past the check valve, it will just build up pressure in the line and brake chamber to release the brakes (leaving the tanks empty).

That check valve can also stick open (or partially open). In that case, the trailer tanks will drain out when the brakes are set. Releasing the spring brakes will be delayed if the trailer tanks need to fill (this is true of any leak that drains the tanks). That is because all the air is going into the tanks and it the whole system builds pressure together.