Volvo 850 12v Outlet

[Dave in Maine]

1. Get after all the contact surfaces with a pencil eraser until you see bright metal. I see rust in your pictures, especially around the center rivet, and that tells me all the contacts have a coating of nonconductive oxide, much of which you probably cannot see.

2. My 850 used a 20A fuse for the lighter. Try a 20A.

3. When you insert the plug into the outlet, try gently twisting it in the socket until you get power.

+1 for cleaning and/or a little wiggle jiggle.

And that FM modulator draws nowhere near
10 amps. A larger fuse wouldn’t be a fix.
IIRC, the rated fuse for the cigarette lighter
( position 30 ) is 10 amps. A higher fuse value
is not a good idea - Things can get melty...

You are correct that putting in a larger fuse than called for in the manual is a suboptimal solution that can lead to trouble. My 96 850's cigarette lighter was rated, per the manual, at 20 amps. OTOH, the lighter circuit on my 09 S60 is rated at 15 amps (which I found out when trying to run an inflator that drew 20, and blew the fuse).

A thorough cleaning of contacts to bright metal - especially that rivet, where the spring-loaded center contact in his plug will make contact - is both in order and likely to resolve the issue.