Gary I'll try your steps.
Charles the aux air compressor is only raising the pressure to 110 then goes off so do you still think it is a problem. One thing I haven't checked is to hear if it is making the noise when the compressor goes off.
Gary I'll try your steps.
Charles the aux air compressor is only raising the pressure to 110 then goes off so do you still think it is a problem. One thing I haven't checked is to hear if it is making the noise when the compressor goes off.
I never found an answer to mine doing this. It sounds just like a fog horn as you say. I think it is air pressure trying to equalize between the canister that serve the drive axel brakes. It just stopped on its own I think or, maybe it stopped after I had all my air bags and Norgen's replaced. Not sure.
i had a similar problem on a bluebird and it was a check valve. just a thought.