It can be as simple as removing the 2 sockets & wiring both leads into a 13pin socket. This assumes you have 12n/12s sockets. If you have only a single 7pin 12n socket then job is easier still.
I'd advise you to get the dedicated volvo kit,around £90 from the volvo dealer. Plug and play in around 20 mins. The dealer may advise that it needs a software download but it doesn at t,all that does is disable the cars rear fog light if the caravan's connected to stop you getting glare off the front of your van.
------------- La Plage Blanche
Camping Solitaire Du lac
Camping Les Bouleaux
Val de Vesle
I would second that...get the dedicated loom. It's all prewired,and plug and play.
that's assuming you want to power the fridge and charger when on the car.
Go and take a look at volvo forums.or and you can get loads of advice on there, and a few dealer discounts too.
I have done the loom option on 2 volvo. ...I had to get software on one to get it activated, but it sounds like yours is already active anyway, so just plug it in.
If you don't want to power the van when on tow, and just want the lights, it's a case of wiring on a 13 pin plug and using the 7 core cable you already have....but like I say you won't get all the extras that the 13pin gives