Is your trailer parking brake released when you are trying to pull the handle? If so this is normal. The symptoms you are describing, the handle pulling back into the valve when you try to pull it out, happens when the trailer brakes are released. The valve is intentionally plumbed this way to ensure the pins stay engaged when the trailer is moving. If your valve handle pulls back in with the parking brake applied, ( no air going to the trailer) I would suspect the valve is bad or the plumbing is incorrect.

The lift cylinder could be leaking internally, letting oil from one side of the cylinder pass to the other allowing the gate to drift down.

Depending on the type of leveling valve you have this could be normal. Some valves are set up to keep the air in the air bags, some exhaust the air from the airbags when the parking brake is set. Some have manual systems where you can inflate or deflate the bags with a lever.

@fleetrepairsolutions6372 well, I know on a flatbed whennyou pull the trl brake, it will decrese the suspension, qnd I swapped on utility reefer 2010, and it does not) it could probably be the way it is.

Here's how you can tell if it's normal or if you have a problem... Look at the leveling valve on the trailer. If it only has 2 air lines connected to it, one on the top coming from the pressure protection valve mounted on the air tank and another on the side of the valve going to the air bags, then your system is operating as intended. If you have a third air line going to a port labeled "Dump" on the valve, then your system is designed to exhaust the airbags when the parking brake is set, and you may have a problem.

@@fleetrepairsolutions6372 thank you will have to check that..m

They only "fail" when wheel end temperatures go high enough to melt the material inside the plug. (it's not really failing, this is what they are designed to do).

Without make and model it's hard to say. Check for any damaged components restricting movement on the non moving side. If all looks good I'd look at the lift cylinder that's not moving. You may just need to bleed the air out of the cylinder. Sometimes the cylinders leak internally, if this is the case it will need to be rebuilt or replaced. Hope this helps!

Appreciate it!

Hello Naji, If you don't have any air in your trailer air tank, and your trailer parking brakes are released (red trailer supply button in cab pushed in) then I would look at the emergency relay valve, usually mounted on the trailer supply tank with the red supply line going to it. Air has to pass though this valve first before it can fill the tank and if it's malfunctioning, it may not allow the tank to fill. Another thing to check would be a blockage in the airline feeding the emergency relay valve. Sometimes bugs crawl in the open gladhands and clog things up.

It would only prevent it if the red emergency/supply gladhand was removed as well. (Or there was a substantial leak in the trailer supply circuit.) The tractor protection valve opens the pathway the service air takes when pressure is sufficient in the supply/emergency circuit. (over 45psi I think) In the example I was giving only the service gladhand was removed, and if a service brake application would be made, air would blow out of the disconnected gladhand. The following link has a good explanation of the TPV from Fanshawe Motive Power. kzbin.info/www/bejne/Y2LZcmR7o7N9kJYfeature=shared

@@fleetrepairsolutions6372 Only the service gladhand needs to be removed. I perform this test every day as part of my pre-trip inspection. No air escapes the service gladhand when I apply the service brakes.

Glad you liked it!

Glad to help

Apologies for the late response. Ensure you are using proper method for pulling blink codes. The steps to pull blink codes is different for every manufacturer, as are the diagnostic codes. For example if I were to pull active codes from a Bendix unit, I would apply constant power to the AUX circuit and cycle brake light power 3 times to get active codes. But if I was pulling codes from a Haldex unit I would do the opposite for active codes...Apply constant power to the brake light circuit and cycle the AUX circuit 3 times. If you are using the correct method to pull blink codes and still can't get the ABS light to blink, you could have a defective ECU. Also check to see if someone has mistakenly wired the ABS light straight into the AUX circuit (blue wire). I've seen this a lot. Hope this helps!

@@fleetrepairsolutions6372 Dude thanks!

@@fleetrepairsolutions6372 dude thank you, I'm a apprentice I've been doing a little truck work but mostly trailer work and you teach me a lot. Keep up the videos they are great!

@@fleetrepairsolutions6372 for a WABCO module do you do trailer aux cycle 3 times? Anything with brake power ?

Thanks for the complement, happy to help! To pull blink codes from a Wabco unit with the ABS light on, you need to power the AUX circuit for 1 second, power off for 1 second, then power back on. No brake light circuit activation with Wabco.

Thanks so much!

Thank you!!

Sorry for the delayed response... All depends on what is wrong with it. Is it leaking air from the damage? You can bypass the system by plugging the lines feeding the valve, (the line from the pressure protection valve and the line connected to the emergency supply) but with without parts like brass fittings you'll have to find some creative, non DOT approved ways to block air flow going to the valve.

Thanks

The Meritor part number for the thermal plug is H2200-02.

I think this should still work. I would mark where the patch will go on the wall and lightly scuff the area first.

Sorry for the delayed response... FMVSS 121 states that the combined volume of all service reservoirs and supply reservoirs shall be at least 12 times the combined volume of all service brake chambers. So you should be able to make 12 brake applications from a fully charged tank.

@@fleetrepairsolutions6372 Thank you, does this also include trailer?

@@peyton.c8399 I believe so... considering the wording is "the combined volume of all service and supply reservoirs. Also FMVSS 121 gives specific regulations just for trailers: "S5.2 Required equipment for trailers. Each trailer shall have the following equipment: S5.2.1 Reservoirs. One or more reservoirs to which the air is delivered from the towing vehicle. S5.2.1.1 The total volume of each service reservoir shall be at least eight times the combined volume of all service brake chambers serviced by that reservoir.

@@fleetrepairsolutions6372 Thank you for your help, hopefully I will pass the red seal this time lol

Doubtful. Given the symptoms SV1 had to be the issue. SV2 controls open and close, after oil is diverted from SV1. The fact that it was only going up and down told me the SV1 was not working.