Definitely suspect the hydraulic fluid. My buzzer would go off when I took a left turn onto a highway ramp Too fast (even when the reservoir was full). So you may not actually need to add fluid (or it wont change anything).
But mine did get to the point where it lost fluid slowly over time (years, not days or months), and one day tried to bring jacks up in the morning, and the thing went to constant alarm. So Ö best to carry some ATF fluid with you, just in caseÖ.