1996 kenworth low air switch?

The switch is behind dash, behind your 9 gauge column! If you still have Air pressure and Brakes release and everything works fine if you take the engine warning module up top out and look at the back of it there should be 6 or 8 really small switches on it, one of those will turn off the buzzer so you don't have to listen to that all the time

 

It would be the plug on the right side of the warning module up top that would go to the low air pressure light! Maybe have a bad wire or bad connection! Could also just need a new warning lamp module up top! Those lights are controlled by small light bulbs that could've burnt out! If you look close you can see you can pull off that thin little black strip on the module to get to the lights! I've had a couple burn out

 

I've got a 99 W900 and a couple of my lights seem to be burned out as well. I pulled off that strip of plastic, but haven't tried removing bulbs yet. Saw them, and didn't think they were replaceable.