I've got a problem with my flow control .it's wired up to the main battery in my van but every now and then it turns it's self off and I have to start the engine up to start it up again. More recently it's been turning it's self off and I'm losing all the power in the van.it's not tuning over.no lights nothing! Then after a few minutes power returns and the van starts up? I bough the van and the system already set up in it a few years ago so I didn't wire it up myself. I'm not really technically minded so excuse me if I'm missing something obvious but any help or advise would be helpful? Thanks.