If this happens after you have been driving and all the lights on the level control panel are flashing. The problem is most likely the Hydraulic level sensor in the Hydraulic tank used by the leveling system. If on the other hand it the alarm sounds only when you put the coach in gear right after releasing the parking brake it could be the park brake switch.
In my 06 Endeavor the leveling system is a Power Gear and the pump and tank are located behind the Dash Air Conditioner condensor which is on the driver side in the compartment between the rear wheel and the electrical compartment. You access the leveling unit by undoing the two Barrel locks on the cover and then the one barrel lock on the condenser fan assembly. It then will swing out of the way and you should be able to access the reservoir. There are two things that can cause the problem low hydraulic fluid level or a bad sensor. Check your manual on how to fill it but mine says once all the jacks are fully retracted loosen the weep hole screw at the back end of the tank and see if fluid comes out. If not then go ahead and add some fluid. I kept doing this and finally found that the sensor had gone bad so had it replaced and have not have the problem since. If your level is fine and the alarm is driving you crazy you can unplug the sensor and the alarm will stop. However be careful because you will not jack down warning if you put it in gear before the jacks are fully retracted.
Dave & Jeri
06 Holiday Rambler Endeavor
TOAD 15 Lincoln MKX