Motorhome auxiliary power

Help needed

I have recently bought an Elddiss 115 motorhome and I am experiencing a problem with the auxiliary power, as there is no 12v power,I have replaced the leisure battery but to no avail. I can switch over to the vehicle battery and all works.

I would appreciate any information/advice.

Cheers

Bob

Moderator Edit:

Bob - you posted this in the Caravan Section so I've moved it here into the Motorhome Section where you're more likely to get responses.