Firstly the control on these is the 12 volt supply so if you have that disconnected this will cause you problems. Did the engineer tell you what or where the problem was?
Yes that was going to be my conclusion but I wanted to be sure the engineer hadn't found an earth short somewhere else - Ian
A pleasure - could I now ask you to rate the information given by selecting from the star rating system at the top of the page, once done you can come back to me for further information at any time if needed. Thank You for using JA and have a great day. Ian