[rogers827]

Having spent a very frustrating afternoon attempting to wire in a dash cam on my 2015 XC70, I thought I would share my findings in the hope it might help fellow members and save them some time and frustration.
I had previously done the same job on my 2010 V70 which turned out to be very easy. I simply removed the cover from the passenger footwell fuse box, found a switched 12V live feed and, by using a piggy back fuse, I had the necessary feed.
Not quite so straight forward on the XC70. The fuse box is easily accessed by pulling the passenger footwell carpet forward. Then you just need to remove the fuse box cover. I believe that this task is now a prerequisite for joining Mensa! An internet search found a number of people with the same problem but there were no answers to be found. Not one to give up, I finally found a photo on eBay that gave up the secret. Even knowing how to remove the cover, I still managed to break one of the piece of s**t lugs because they are so brittle and you need to release the 2 lugs together. If you look at the first photo, you can see the 2 subject lugs highlighted. You need to insert a thin, flat piece of metal into each of the 2 narrow slots in the bottom front face of the cover. Then push back the lugs at the same time to release them, and wrestle the cover off. I only retracted one lug and broke the other one. It might work with 2 solid, stout tie wraps if you cut the thin pointy ends off, but there is very little movement of the lugs, so tie wraps might not be strong enough.
The next problem was finding a switched 12V feed. I used my trusty multi-meter and did some testing. I checked that the fuel filler flap would not open until the ignition was in the first position, so that was the one to try first. Unfortunately, from my findings I believe it is switched through a relay, because there was no live feed from that fuse at all, regardless of ignition switch position. Nearly all of the other fuses in the fuse box were constantly live and not switched via the ignition. The couple that were not live were the same as the fuel filler flap. By this time I was very frustrated & had very sore elbows! It is tricky to use the tester in the footwell without your elbows taking a lot of your weight!
An internet search seemed to confirm my findings, so I then began to search for an alternative 12V feed. Some people had obtained a feed from the engine bay fuse box and took a wire through the bulkhead grommets. Others had removed the centre console to piggyback a feed from the console 12V socket. It was whilst I was checking other methods that I found the answer. I discovered a post from the USA which stated that the unused Fuse Socket No 2 on the footwell fuse box only becomes live when you unlock the car. It then switches itself off about 5 minutes after locking the car. Please see the second photo. How emgrock1 on Sweedspeed discovered this quirk I do not know, but I am very grateful that he posted the info for me to find. I hope this also helps if you are tackling a similar job on an XC70. I think it may well apply to other Volvo Models. Please leave a comment if you find out that it does?
If you can't find a suitable earth point for the job, my final piece of advice it to drill a 3-4.0mm ish hole in one of the white metal brackets at the base of the fuse box. You can then attach the earth lead for your supply, using a self tapper and a washer. Just make sure there are no cables behind the bracket before drilling.