First check your jack reservoir, but the alarm is most likely coming from your parking brake. It's a known problem. Often it will stop after you start driving. It can sometimes be checked (diagnosed) by pushing the Parking Brake knob down VERY firmly. The bad switch is attached to the bottom of the Parking Brake switch and by pushing down firmly will make it work properly.
The culprit is called a Nason switch and looks like this below, item #2. In order to access it, you have to pull the side panel, near the driver's left knee and then unscrew the three screws holding the parking brake in place. Be careful, they have nuts on the ends and can fall down into the jumble of wiring. Once the Parking Brake is removed from the shift panel, you'll see air hoses attached and the switch on the bottom with three wires, about the size of your thumb.
Monaco parts, which is still open, used to sell the switch, years ago, it was about $45.00.
The photos below are from an old email I have.
Linear Mode
