This site has the pinouts for the radio connectors (you have to read the
text to figure out which is 12+ to battery):

http://volvospeed.com/Repair/radiocon.htm

You can check for voltage with a meter.

Parking lights are for parking. In California, it is illegal
to drive with just the parking lights on since they indicate
you are parked and not moving. Also, on some European cars you
can set the parking lights on one side or the other (on newer
BMWS you push the turn signal down for just left side and up for
just right side and this works as long as ignition is off). Not
sure if Volvos do this. Why one side? -- I think you are supposed to
set the outside edge of the car (the side protruding into the roadway)
to help drivers avoid hitting your parked car. I guess they have a lot
of narrow, dark roads in Europe

The radio code should only be required when you disconnect the battery. since it is not, then the system is failing to retain your code in memory. This should be checked out.

I do not know what you mean by lights in parked position. Please clarify what switch you are talking about and whether the ignition is on or off at the time.

Delgado

In the radio situation you may have a more serious problem. The code is only called for if power has been disconnected to the radio. You could have an electrical problem in the radio feed, check the fuses to start with and go on from there. There are two power feeds to the radio, one keeps the settings stored and is almost a direct connection to the battery. The second power feed from the ignition switch powers up the radio.
As to the parking lights staying on this is normal practice for the European market, if you are parked more than a certain distance from a street light you are required to exhibit side lights at night. Obviously they must stay on when the key is removed.
John Scales (1996 850R)