I mean the the regulator / cut off valve on the diesel high pressure pump. It has 12v from from pin 8 of the black plug in engine bay fuse box and 3.5v from ECU brown plug pin M4. I think this is supposed to be a negative but I can't understand why it has 2 different voltage
Thank you for your reply, There is no fuel in the fuel rail so I suspect the new (ebay) pressure switch in the fuel rail faulty. I will go and get a good quality one today and check the data again. I have fitted another H/P pump complete with regulator from a working engine.
Fuel return good
Thank you every body for your input. Went out and brought a quality fuel pressure sensor. Plugged it in the harness and could see the difference straight away in PP2000. fitted and now van running again.