Hard lesson learned...When you get an alarm buzzer going off in your ear, and your not sure what it is and it won't go out....back away from the hammer and do not give in to the impulse to shut it off the easy way!
On a serious note, I had one of those going for a while. My back door sensor had stuck and it thought my door was open. I disconnected the sensor, cleaned it and put back in. Problem solved. could also be an air leak somewhere is not letting tanks fill all the way. On most
systems if you don't get past 65lbs, it isn't going to go off. Can you move the bus when it is buzzing? also, will your airbrake knob push in and stay? knob will usually
not stay in if enough air isn't built up.
Keep on playing with it while wearing ear muffs.
As you have probably noticed, If you post an issue here, you will be flooded with possible answers to the problem as well as many different ideas as to how to fix. I love it here!
Welcome to the insanely wonderful world of bussin.