2008 KW T660 Parking Brake light

[Matt]

I'm going to have some time off at the end of the week and wanted to tackle this nagging issue. When I set my parking brake valve, the light on the dash doesn't illuminate and my daytime running lights stay on. When I open the door the alarm chimes and flashes the park brake light as if to remind me to set the brake even though it's set. It doesn't do this every single time but majority of the time. I figure it's a pressure switch that controls it that's giving trouble. Does anyone know the location of these switches?