DenzO,

The lighters in Volvos only work when the electrical system is on, position I on the ignition. You will either need to re-wire the sockets to bypass the ignition or run power directly from the battery to an auxilliary socket.

This is what I and most others have done. You can get the parts--fuse, wire, connectors and lighter socket--from Radio Shack for less than $20.00US.

There is easy access through the firewall plug and the installation is fairly straightforward.

Post if you need further instructions.

Bryan