Air leak in tractor protection valve

Ride height valve? I don't see the correlation between the two. Could someone someone explain how.

 

Maybe the leveling valve was leaking, and he was hearing the air rush thru the dash valve, which made him think the dash valve was leaking. Only thing I can think of.

 

Unless it was the air switch to dump the tractor suspension.

 

Yes that's what my truck is doing when i park it stops leaking air

 

Is it the tractor protection valve or the MV3 valve which is leaking? Because they’re not the same thing.

I wouldn’t say the shop personnel are blowing it off, but when you can’t duplicate the issue on something which can multiple possible reasons for being, it kinda leaves you at an impasse. You’re not talking about sometime that’ll record DTCs, so you can’t plug a computer in and find historical that’ll tell you what faults have been triggered and how many times.

If it’s the tractor protection valve, it’ll typically be either a failing valve or backfeed from the trailer brakes on account of a bad quick release or relay valve. The dash valve (MV3), if it’s not one of the valves themselves, the emergency side of your likely culprit, since any backfeeding air from the service side would go through the foot valve.

 

This is currently happening to me...its my trailer brake...when its pushed in it starts making this loud hissing noise...when pulled out nothing...the #s on the dash both drop..one comes right up...but the other takes a good long while to get back up...does anyone know the answer to this???