On Sep 30, 2021, at 11:43 AM, Arno Luijten <arno.luijten@...> wrote:

Hi Scott,

The brain of this thing is fairly rudimentary so not too likely to fail unless water has entered the enclosure or the connectors.
The way they routed the sensor cables is not the best leaving the connectors in a place where seawater easily gets.
So your first step is checking the wires and other parts for corrosion and water ingress.
As you may have noticed the sensors have a light build in that lights up when the sensor senses metal.
There are four sensors in total. Two are used to sense the height of the passerelle and the middle (level) position. They are prone to mis-adjustment because of the way they are mounted on metal brackets. The logic is that both must be actuated at the level-position of the gangway. So there is a very small area of possible positions for which both are actuated. This can give you problems if the cylinders are not working properly.
The way it works is that the pump pushes oil that gets routed by the electromagnetic valves. Behind these valves there are adjustable restrictors that limit the oil-flow to the cylinders. These restrictors need to be adjusted in such a way that the up-down speed is not too high for the system to stop the motion at the point where both sensors are actuated. In my case I had problems with the seals inside the cylinders that made this into a total hell and it took us moths of trial and error to realize the cylinders needed to be overhauled.
Reading what you are saying, my guess is that the brain is getting information that both up-down sensors are active all the time and the rotation sensor is also active all the time.
On the brainbox there are LEDs that will tell you which sensors are actuated according to the brainbox. From memory they are marked X,Y,W and V. When the passerelle is tucked away only one of them should be dim and three should light up. The dim one is the rotational sensor that only lights up if the passerelle is at an angle of 80-100 degrees with the stern. Only at that point the up-down and extend functions will operate. 
So if your rotational sensor is active all the time you can really crash your passerelle into the GRP slot. The lights on the brainbox can really help you identifying the problem. As said before the connectors and brainbox enclosure are suspect for creating false signals. Compare the signal light at the back of the sensors with the lights in the brainbox.

Hope this helps,

Arno Luijten,
SV Luna,
A54-121