The alarm has gone off before when i was lifting but it was because i had a leak in a hose. this time it's when driving no w/ no load maybe at 1/3 throtle
The best would be to install a pressure guage in the sender port and observe your charge pressure. It will fluctuate quite a bit. Lowest readings will be when you bottom a cylinder on the extend stroke, or nearly stall the the engine with the drives.
Just cruising along like you mention the reading should be fairly stable
Not sure on yours, I believe my 553 was @ 100psi. warning at 25??
It jumped around alot between 60 and 100 depending on what the operator was doing.
Would flicker momentarily if you bottomed out a cylinder.
Could be as simple as a worn through wire getting a ground that turns the light on, or bad sender, or many hyd issues.
Does the machine seem to operate fine? or can you feel it “lay down” when the light comes on?
Ken