Help needed Please! I have a 21A and a 17A NE287 factory fitted to Mobilvetta. Trying to figure out how these work together. It appears that they are connected in parallel and only one is active if there is a low power requirement. Does any one have expert knowledge or experience of this? Manual I have is not technical enough and can’t find any more information. They are located behind a panel so really hard to work on without dismantling part of the van! Thanks in advance - Ian