Hi everybody!
I searched but haven't found the exact same problem.
I just bought a 2004.5 Volvo S40 2.4i.
All lights were working fine, but now parking/side lights (2 bulbs in each headlight assembly) and tail lights doesn't work anymore. License plate light is out too. HID low beam and high beam work, turn signals work, front and rear fog lights work... Brake lights work, although the right one and the third one seem to turn off right after turning on (like a flash). Left one works fine.

I checked the fused related to lights, but they seem fine. So do the bulbs (would be surprising that more than 7 of them blow out at the same time anyway)
Do you think it can be the light switch? CEM?
Thank you for your help...

 

Your check for a fuse was canny. Look for discussions about relays on the CEM. Remedies range from the standard dealer "put in a new one for $2000" to cleaning CEM plug contacts or replacing the actual relays, which are standard electronics parts.

In the US, the CEM is on the right side under the glove box, with a MASSIVE system plug attaching it to the car's wiring harness.

 

Thank you, I will find the CEM, clean its contacts and have a look at the relays.
I've ordered a light switch as i found a cheap one, but I have to wait for it. I hope it will be as simple as that...
I'll let you know how it works.