Comicman

I bought a 300C 2006 & began having problems starting when the weather got colder in December. Replaced the Module & the Glow Plugs but now have the fault code U0106 saying there is no connection from the ECU to the Module. As the Module has 12v constantly, is it an earth signal that is sent from the ECU & how can I check the signal without removing the ECU (Big Job). Has anyone out there had the same problem? Any advice would be gratefully received. THANKS IN ADVANCE