W211 injector problem

[ES5 4 NOW]

It seems that cylinder 2 injector isn't playing ball
Diagnostic says cylinder 2 misfire.
Changed all plugs new.changed coilpack leads and injector from anther cylinder and it still says cylinder 2 misfire.put a stethoscope on injectors and all seem to tick bar no2.
Which I think means a wiring problem?is there any fuse or relays to check or has anyone had similar.

Thanks

 

[ES5 4 NOW]

Also what voltage should the injector wiring produce?