we have some kalmar shop manuals at the shop
i'll see if i can swing by there and check to see if we have this one
maybe there will be some troubleshooting guides in it that will help some.
I'll post back here when i get it.

one other thing to consider is if you bypass the sensor it may see that as the same problem, low accumulator pressure.
Is this accumulator one that is gas charged? i would check that as well. Maybe the pressure in it is low?