Volvo 2008 C30 Owner's Manual page 192

All bulbs in the taillight cluster can be replaced from the cargo area. To access the bulb holders:
1. Switch off all lights and turn the key to position 0.
2. Remove the covers (A or B) in the left/right panels to access the bulb holders.
3. Disconnect the wiring connector from the affected bulb holder.
4. Press the catches together and pull out the bulb holder.
5. Replace the defective bulb.
6. Press the wiring connector back into position.
7. Press the bulb holder into place and reinstall the cover.
Location of tail light bulbs