A noise (and smoke) is coming out from this component (attached picture) on my 2007 Mk6 Ford transit whenever the back battery is connected. I thought the back battery under the seat was just for the starter motor and the front one for everything else. Does anyone know what component this is and what all the components are that are attached to the back battery? (I suspect it could be a diesel heater for heating the back and the smoke exhaust gases, but am not sure) Could the problem be a faulty relay stuck in the "on" position?
Here is also a video of what's happening: https://1drv.ms/v/s!Agg2m_iROav7gbNbQgq ... A?e=PA6fTG
Any help is greatly appreciated!