Well, looking at the video the PTU is explained like a simple on/off valve to let hydrolic oil from the
higher pressure system (e.g. yellow correctly at 3000psi) flow to the lower pressure system
(eg. green at 2700psi) and thus supplying energy to it. But the dog like sound heared is that
of a motor running forward/backward/forward/backward and so on. So is the PTU a pump acually?
But this would not make much sense as the failed system should have a pressure lower than the
OK system leading to an automatic flow in the right direction...