2013 Volvo d13 fault code spn 3509 fmi 4

Does anyone know what spn 3509 fm I 4 fault code means.2013 Volvo d13 lost turbo boost in the penn hills.Any help appreciated

 

This is a code for the boost pressure sensor low voltage.After 3 visits to the dealer a new turbo 2 new boost pressure sensors and 2 new turbo speed sensors and 6000 $ spent for repairs I still have the same problem.Loosing boost pressure gauge goes down to 0 after I restart the truck goes back to normal.Any help is appreciated

 

Must be a bad wire or a bad connector but how come they can't find it at the dealer.Three times they say they have checked the harness and its good.Visualy I don't see any damage on the wires on the outside except for the connector of this sensor being little loose.I zip tied it and I don't have the check engine light anymore.I doubt that will fix it but it's a start.As soon as I deliver my load tomorrow I'll go through the wires and inspect them thoroughly.I've had these problems with my old truck it's a nightmare.I thought I was gonna get a break from this kind of stuff buying a new truck.Its a 2013 barely 270K miles on it I bought it brand new wires are not that old

 

Still working on it.Fan clutch switch relocated possibly shorting the 5v supply due to vibration.Did 2k miles since running ok so far but it's early to tell.Something is shorting that 5v supply line and shorting the boost pressure sensor.It is still a work in progress but it's been driving me crazy